(Slip Opinion) OCTOBER TERM, 2017 1
Syllabus
NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
being done in connection with this case, at the time the opinion is issued.
The syllabus constitutes no part of the opinion of the Court but has been
prepared by the Reporter of Decisions for the convenience of the reader.
See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.
SUPREME COURT OF THE UNITED STATES
Syllabus
CARPENTER v. UNITED STATES
CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
THE SIXTH CIRCUIT
No. 16–402. Argued November 29, 2017—Decided June 22, 2018
Cell phones perform their wide and growing variety of functions by con-
tinuously connecting to a set of radio antennas called “cell sites.”
Each time a phone connects to a cell site, it generates a time-stamped
record known as cell-site location information (CSLI). Wireless carri-
ers collect and store this information for their own business purposes.
Here, after the FBI identified the cell phone numbers of several rob-
bery suspects, prosecutors were granted court orders to obtain the
suspects’ cell phone records under the Stored Communications Act.
Wireless carriers produced CSLI for petitioner Timothy Carpenter’s
phone, and the Government was able to obtain 12,898 location points
cataloging Carpenter’s movements over 127 days—an average of 101
data points per day. Carpenter moved to suppress the data, arguing
that the Government’s seizure of the records without obtaining a
warrant supported by probable cause violated the Fourth Amend-
ment. The District Court denied the motion, and prosecutors used
the records at trial to show that Carpenter’s phone was near four of
the robbery locations at the time those robberies occurred. Carpen-
ter was convicted. The Sixth Circuit affirmed, holding that Carpen-
ter lacked a reasonable expectation of privacy in the location infor-
mation collected by the FBI because he had shared that information
with his wireless carriers.
Held:
1. The Government’s acquisition of Carpenter’s cell-site records
was a Fourth Amendment search. Pp. 4–18.
(a) The Fourth Amendment protects not only property interests
but certain expectations of privacy as well. Katz v. United States, 389
U. S. 347, 351. Thus, when an individual “seeks to preserve some-
thing as private,” and his expectation of privacy is “one that society is
2 CARPENTER v. UNITED STATES
Syllabus
prepared to recognize as reasonable,” official intrusion into that
sphere generally qualifies as a search and requires a warrant sup-
ported by probable cause. Smith v. Maryland, 442 U. S. 735, 740 (in-
ternal quotation marks and alterations omitted). The analysis re-
garding which expectations of privacy are entitled to protection is
informed by historical understandings “of what was deemed an un-
reasonable search and seizure when [the Fourth Amendment] was
adopted.” Carroll v. United States, 267 U. S. 132, 149. These Found-
ing-era understandings continue to inform this Court when applying
the Fourth Amendment to innovations in surveillance tools. See, e.g.,
Kyllo v. United States, 533 U. S. 27. Pp. 4–7.
(b) The digital data at issue—personal location information
maintained by a third party—does not fit neatly under existing prec-
edents but lies at the intersection of two lines of cases. One set ad-
dresses a person’s expectation of privacy in his physical location and
movements. See, e.g., United States v. Jones, 565 U. S. 400 (five Jus-
tices concluding that privacy concerns would be raised by GPS track-
ing). The other addresses a person’s expectation of privacy in infor-
mation voluntarily turned over to third parties. See United States v.
Miller, 425 U. S. 435 (no expectation of privacy in financial records
held by a bank), and Smith, 442 U. S. 735 (no expectation of privacy
in records of dialed telephone numbers conveyed to telephone compa-
ny). Pp. 7–10.
(c) Tracking a person’s past movements through CSLI partakes
of many of the qualities of GPS monitoring considered in Jones—it is
detailed, encyclopedic, and effortlessly compiled. At the same time,
however, the fact that the individual continuously reveals his loca-
tion to his wireless carrier implicates the third-party principle of
Smith and Miller. Given the unique nature of cell-site records, this
Court declines to extend Smith and Miller to cover them. Pp. 10–18.
(1) A majority of the Court has already recognized that indi-
viduals have a reasonable expectation of privacy in the whole of their
physical movements. Allowing government access to cell-site rec-
ords—which “hold for many Americans the ‘privacies of life,’ ” Riley v.
California, 573 U. S. ___, ___—contravenes that expectation. In fact,
historical cell-site records present even greater privacy concerns than
the GPS monitoring considered in Jones: They give the Government
near perfect surveillance and allow it to travel back in time to retrace
a person’s whereabouts, subject only to the five-year retention poli-
cies of most wireless carriers. The Government contends that CSLI
data is less precise than GPS information, but it thought the data ac-
curate enough here to highlight it during closing argument in Car-
penter’s trial. At any rate, the rule the Court adopts “must take ac-
count of more sophisticated systems that are already in use or in
Cite as: 585 U. S. ____ (2018) 3
Syllabus
development,” Kyllo, 533 U. S., at 36, and the accuracy of CSLI is
rapidly approaching GPS-level precision. Pp. 12–15.
(2) The Government contends that the third-party doctrine
governs this case, because cell-site records, like the records in Smith
and Miller, are “business records,” created and maintained by wire-
less carriers. But there is a world of difference between the limited
types of personal information addressed in Smith and Miller and the
exhaustive chronicle of location information casually collected by
wireless carriers.
The third-party doctrine partly stems from the notion that an indi-
vidual has a reduced expectation of privacy in information knowingly
shared with another. Smith and Miller, however, did not rely solely
on the act of sharing. They also considered “the nature of the partic-
ular documents sought” and limitations on any “legitimate ‘expecta-
tion of privacy’ concerning their contents.” Miller, 425 U. S., at 442.
In mechanically applying the third-party doctrine to this case the
Government fails to appreciate the lack of comparable limitations on
the revealing nature of CSLI.
Nor does the second rationale for the third-party doctrine—
voluntary exposure—hold up when it comes to CSLI. Cell phone lo-
cation information is not truly “shared” as the term is normally un-
derstood. First, cell phones and the services they provide are “such a
pervasive and insistent part of daily life” that carrying one is indis-
pensable to participation in modern society. Riley, 573 U. S., at ___.
Second, a cell phone logs a cell-site record by dint of its operation,
without any affirmative act on the user’s part beyond powering up.
Pp. 15–17.
(d) This decision is narrow. It does not express a view on matters
not before the Court; does not disturb the application of Smith and
Miller or call into question conventional surveillance techniques and
tools, such as security cameras; does not address other business rec-
ords that might incidentally reveal location information; and does not
consider other collection techniques involving foreign affairs or na-
tional security. Pp. 17–18.
2. The Government did not obtain a warrant supported by proba-
ble cause before acquiring Carpenter’s cell-site records. It acquired
those records pursuant to a court order under the Stored Communi-
cations Act, which required the Government to show “reasonable
grounds” for believing that the records were “relevant and material to
an ongoing investigation.” 18 U. S. C. §2703(d). That showing falls
well short of the probable cause required for a warrant. Consequent-
ly, an order issued under §2703(d) is not a permissible mechanism for
accessing historical cell-site records. Not all orders compelling the
production of documents will require a showing of probable cause. A
4 CARPENTER v. UNITED STATES
Syllabus
warrant is required only in the rare case where the suspect has a le-
gitimate privacy interest in records held by a third party. And even
though the Government will generally need a warrant to access
CSLI, case-specific exceptions—e.g., exigent circumstances—may
support a warrantless search. Pp. 18–22.
819 F. 3d 880, reversed and remanded.
ROBERTS, C. J., delivered the opinion of the Court, in which GINS-
BURG, BREYER, SOTOMAYOR, and KAGAN, JJ., joined. KENNEDY, J., filed a
dissenting opinion, in which THOMAS and ALITO, JJ., joined. THOMAS, J.,
filed a dissenting opinion. ALITO, J., filed a dissenting opinion, in which
THOMAS, J., joined. GORSUCH, J., filed a dissenting opinion.
Cite as: 585 U. S. ____ (2018) 1
Opinion of the Court
NOTICE: This opinion is subject to formal revision before publication in the
preliminary print of the United States Reports. Readers are requested to
notify the Reporter of Decisions, Supreme Court of the United States, Wash-
ington, D. C. 20543, of any typographical or other formal errors, in order
that corrections may be made before the preliminary print goes to press.
SUPREME COURT OF THE UNITED STATES
_________________
No. 16–402
_________________
TIMOTHY IVORY CARPENTER, PETITIONER v.
UNITED STATES
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE SIXTH CIRCUIT
[June 22, 2018]
CHIEF JUSTICE ROBERTS delivered the opinion of the
Court.
This case presents the question whether the Govern-
ment conducts a search under the Fourth Amendment
when it accesses historical cell phone records that provide
a comprehensive chronicle of the user’s past movements.
I
A
There are 396 million cell phone service accounts in the
United States—for a Nation of 326 million people. Cell
phones perform their wide and growing variety of func-
tions by connecting to a set of radio antennas called “cell
sites.” Although cell sites are usually mounted on a tower,
they can also be found on light posts, flagpoles, church
steeples, or the sides of buildings. Cell sites typically have
several directional antennas that divide the covered area
into sectors.
Cell phones continuously scan their environment look-
ing for the best signal, which generally comes from the
closest cell site. Most modern devices, such as
smartphones, tap into the wireless network several times
2 CARPENTER v. UNITED STATES
Opinion of the Court
a minute whenever their signal is on, even if the owner is
not using one of the phone’s features. Each time the
phone connects to a cell site, it generates a time-stamped
record known as cell-site location information (CSLI). The
precision of this information depends on the size of the
geographic area covered by the cell site. The greater the
concentration of cell sites, the smaller the coverage area.
As data usage from cell phones has increased, wireless
carriers have installed more cell sites to handle the traffic.
That has led to increasingly compact coverage areas,
especially in urban areas.
Wireless carriers collect and store CSLI for their own
business purposes, including finding weak spots in their
network and applying “roaming” charges when another
carrier routes data through their cell sites. In addition,
wireless carriers often sell aggregated location records to
data brokers, without individual identifying information of
the sort at issue here. While carriers have long retained
CSLI for the start and end of incoming calls, in recent
years phone companies have also collected location infor-
mation from the transmission of text messages and rou-
tine data connections. Accordingly, modern cell phones
generate increasingly vast amounts of increasingly precise
CSLI.
B
In 2011, police officers arrested four men suspected of
robbing a series of Radio Shack and (ironically enough) T-
Mobile stores in Detroit. One of the men confessed that,
over the previous four months, the group (along with a
rotating cast of getaway drivers and lookouts) had robbed
nine different stores in Michigan and Ohio. The suspect
identified 15 accomplices who had participated in the
heists and gave the FBI some of their cell phone numbers;
the FBI then reviewed his call records to identify addi-
tional numbers that he had called around the time of the
Cite as: 585 U. S. ____ (2018) 3
Opinion of the Court
robberies.
Based on that information, the prosecutors applied for
court orders under the Stored Communications Act to
obtain cell phone records for petitioner Timothy Carpenter
and several other suspects. That statute, as amended in
1994, permits the Government to compel the disclosure of
certain telecommunications records when it “offers specific
and articulable facts showing that there are reasonable
grounds to believe” that the records sought “are relevant
and material to an ongoing criminal investigation.” 18
U. S. C. §2703(d). Federal Magistrate Judges issued two
orders directing Carpenter’s wireless carriers—MetroPCS
and Sprint—to disclose “cell/site sector [information] for
[Carpenter’s] telephone[ ] at call origination and at call
termination for incoming and outgoing calls” during the
four-month period when the string of robberies occurred.
App. to Pet. for Cert. 60a, 72a. The first order sought 152
days of cell-site records from MetroPCS, which produced
records spanning 127 days. The second order requested
seven days of CSLI from Sprint, which produced two days
of records covering the period when Carpenter’s phone was
“roaming” in northeastern Ohio. Altogether the Govern-
ment obtained 12,898 location points cataloging Carpen-
ter’s movements—an average of 101 data points per day.
Carpenter was charged with six counts of robbery and
an additional six counts of carrying a firearm during a
federal crime of violence. See 18 U. S. C. §§924(c), 1951(a).
Prior to trial, Carpenter moved to suppress the cell-site
data provided by the wireless carriers. He argued that the
Government’s seizure of the records violated the Fourth
Amendment because they had been obtained without a
warrant supported by probable cause. The District Court
denied the motion. App. to Pet. for Cert. 38a–39a.
At trial, seven of Carpenter’s confederates pegged him
as the leader of the operation. In addition, FBI agent
Christopher Hess offered expert testimony about the cell-
4 CARPENTER v. UNITED STATES
Opinion of the Court
site data. Hess explained that each time a cell phone taps
into the wireless network, the carrier logs a time-stamped
record of the cell site and particular sector that were used.
With this information, Hess produced maps that placed
Carpenter’s phone near four of the charged robberies. In
the Government’s view, the location records clinched the
case: They confirmed that Carpenter was “right where the
. . . robbery was at the exact time of the robbery.” App.
131 (closing argument). Carpenter was convicted on all
but one of the firearm counts and sentenced to more than
100 years in prison.
The Court of Appeals for the Sixth Circuit affirmed. 819
F. 3d 880 (2016). The court held that Carpenter lacked a
reasonable expectation of privacy in the location infor-
mation collected by the FBI because he had shared that
information with his wireless carriers. Given that cell
phone users voluntarily convey cell-site data to their
carriers as “a means of establishing communication,” the
court concluded that the resulting business records are not
entitled to Fourth Amendment protection. Id., at 888
(quoting Smith v. Maryland, 442 U. S. 735, 741 (1979)).
We granted certiorari. 582 U. S. ___ (2017).
II
A
The Fourth Amendment protects “[t]he right of the
people to be secure in their persons, houses, papers, and
effects, against unreasonable searches and seizures.” The
“basic purpose of this Amendment,” our cases have recog-
nized, “is to safeguard the privacy and security of individ-
uals against arbitrary invasions by governmental offi-
cials.” Camara v. Municipal Court of City and County of
San Francisco, 387 U. S. 523, 528 (1967). The Founding
generation crafted the Fourth Amendment as a “response
to the reviled ‘general warrants’ and ‘writs of assistance’ of
the colonial era, which allowed British officers to rum-
Cite as: 585 U. S. ____ (2018) 5
Opinion of the Court
mage through homes in an unrestrained search for evi-
dence of criminal activity.” Riley v. California, 573 U. S.
___, ___ (2014) (slip op., at 27). In fact, as John Adams
recalled, the patriot James Otis’s 1761 speech condemning
writs of assistance was “the first act of opposition to the
arbitrary claims of Great Britain” and helped spark the
Revolution itself. Id., at ___–___ (slip op., at 27–28) (quot-
ing 10 Works of John Adams 248 (C. Adams ed. 1856)).
For much of our history, Fourth Amendment search
doctrine was “tied to common-law trespass” and focused on
whether the Government “obtains information by physi-
cally intruding on a constitutionally protected area.”
United States v. Jones, 565 U. S. 400, 405, 406, n. 3 (2012).
More recently, the Court has recognized that “property
rights are not the sole measure of Fourth Amendment
violations.” Soldal v. Cook County, 506 U. S. 56, 64
(1992). In Katz v. United States, 389 U. S. 347, 351 (1967),
we established that “the Fourth Amendment protects
people, not places,” and expanded our conception of the
Amendment to protect certain expectations of privacy as
well. When an individual “seeks to preserve something as
private,” and his expectation of privacy is “one that society
is prepared to recognize as reasonable,” we have held that
official intrusion into that private sphere generally quali-
fies as a search and requires a warrant supported by
probable cause. Smith, 442 U. S., at 740 (internal quota-
tion marks and alterations omitted).
Although no single rubric definitively resolves which
expectations of privacy are entitled to protection,1 the
——————
1 JUSTICE KENNEDY believes that there is such a rubric—the “proper-
ty-based concepts” that Katz purported to move beyond. Post, at 3
(dissenting opinion). But while property rights are often informative,
our cases by no means suggest that such an interest is “fundamental”
or “dispositive” in determining which expectations of privacy are
legitimate. Post, at 8–9. JUSTICE THOMAS (and to a large extent
JUSTICE GORSUCH) would have us abandon Katz and return to an
6 CARPENTER v. UNITED STATES
Opinion of the Court
analysis is informed by historical understandings “of what
was deemed an unreasonable search and seizure when
[the Fourth Amendment] was adopted.” Carroll v. United
States, 267 U. S. 132, 149 (1925). On this score, our cases
have recognized some basic guideposts. First, that the
Amendment seeks to secure “the privacies of life” against
“arbitrary power.” Boyd v. United States, 116 U. S. 616,
630 (1886). Second, and relatedly, that a central aim of
the Framers was “to place obstacles in the way of a too
permeating police surveillance.” United States v. Di Re,
332 U. S. 581, 595 (1948).
We have kept this attention to Founding-era under-
standings in mind when applying the Fourth Amendment
to innovations in surveillance tools. As technology has
enhanced the Government’s capacity to encroach upon
areas normally guarded from inquisitive eyes, this Court
has sought to “assure[ ] preservation of that degree of
privacy against government that existed when the Fourth
Amendment was adopted.” Kyllo v. United States, 533
U. S. 27, 34 (2001). For that reason, we rejected in Kyllo a
“mechanical interpretation” of the Fourth Amendment and
held that use of a thermal imager to detect heat radiating
from the side of the defendant’s home was a search. Id., at
35. Because any other conclusion would leave homeown-
ers “at the mercy of advancing technology,” we determined
that the Government—absent a warrant—could not capi-
talize on such new sense-enhancing technology to explore
——————
exclusively property-based approach. Post, at 1–2, 17–21 (THOMAS J.,
dissenting); post, at 6–9 (GORSUCH, J., dissenting). Katz of course
“discredited” the “premise that property interests control,” 389 U. S., at
353, and we have repeatedly emphasized that privacy interests do not
rise or fall with property rights, see, e.g., United States v. Jones, 565
U. S. 400, 411 (2012) (refusing to “make trespass the exclusive test”);
Kyllo v. United States, 533 U. S. 27, 32 (2001) (“We have since decou-
pled violation of a person’s Fourth Amendment rights from trespassory
violation of his property.”). Neither party has asked the Court to
reconsider Katz in this case.
Cite as: 585 U. S. ____ (2018) 7
Opinion of the Court
what was happening within the home. Ibid.
Likewise in Riley, the Court recognized the “immense
storage capacity” of modern cell phones in holding that
police officers must generally obtain a warrant before
searching the contents of a phone. 573 U. S., at ___ (slip
op., at 17). We explained that while the general rule
allowing warrantless searches incident to arrest “strikes
the appropriate balance in the context of physical objects,
neither of its rationales has much force with respect to”
the vast store of sensitive information on a cell phone. Id.,
at ___ (slip op., at 9).
B
The case before us involves the Government’s acquisi-
tion of wireless carrier cell-site records revealing the
location of Carpenter’s cell phone whenever it made or
received calls. This sort of digital data—personal location
information maintained by a third party—does not fit
neatly under existing precedents. Instead, requests for
cell-site records lie at the intersection of two lines of cases,
both of which inform our understanding of the privacy
interests at stake.
The first set of cases addresses a person’s expectation of
privacy in his physical location and movements. In United
States v. Knotts, 460 U. S. 276 (1983), we considered the
Government’s use of a “beeper” to aid in tracking a vehicle
through traffic. Police officers in that case planted a
beeper in a container of chloroform before it was pur-
chased by one of Knotts’s co-conspirators. The officers
(with intermittent aerial assistance) then followed the
automobile carrying the container from Minneapolis to
Knotts’s cabin in Wisconsin, relying on the beeper’s signal
to help keep the vehicle in view. The Court concluded that
the “augment[ed]” visual surveillance did not constitute a
search because “[a] person traveling in an automobile on
public thoroughfares has no reasonable expectation of
8 CARPENTER v. UNITED STATES
Opinion of the Court
privacy in his movements from one place to another.” Id.,
at 281, 282. Since the movements of the vehicle and its
final destination had been “voluntarily conveyed to anyone
who wanted to look,” Knotts could not assert a privacy
interest in the information obtained. Id., at 281.
This Court in Knotts, however, was careful to distin-
guish between the rudimentary tracking facilitated by the
beeper and more sweeping modes of surveillance. The
Court emphasized the “limited use which the government
made of the signals from this particular beeper” during a
discrete “automotive journey.” Id., at 284, 285. Signifi-
cantly, the Court reserved the question whether “different
constitutional principles may be applicable” if “twenty-four
hour surveillance of any citizen of this country [were]
possible.” Id., at 283–284.
Three decades later, the Court considered more sophis-
ticated surveillance of the sort envisioned in Knotts and
found that different principles did indeed apply. In United
States v. Jones, FBI agents installed a GPS tracking de-
vice on Jones’s vehicle and remotely monitored the vehi-
cle’s movements for 28 days. The Court decided the case
based on the Government’s physical trespass of the vehi-
cle. 565 U. S., at 404–405. At the same time, five Justices
agreed that related privacy concerns would be raised by,
for example, “surreptitiously activating a stolen vehicle
detection system” in Jones’s car to track Jones himself, or
conducting GPS tracking of his cell phone. Id., at 426, 428
(ALITO, J., concurring in judgment); id., at 415
(SOTOMAYOR, J., concurring). Since GPS monitoring of a
vehicle tracks “every movement” a person makes in that
vehicle, the concurring Justices concluded that “longer
term GPS monitoring in investigations of most offenses
impinges on expectations of privacy”—regardless whether
those movements were disclosed to the public at large.
Id., at 430 (opinion of ALITO, J.); id., at 415 (opinion of
Cite as: 585 U. S. ____ (2018) 9
Opinion of the Court
SOTOMAYOR, J.).2
In a second set of decisions, the Court has drawn a line
between what a person keeps to himself and what he
shares with others. We have previously held that “a per-
son has no legitimate expectation of privacy in information
he voluntarily turns over to third parties.” Smith, 442
U. S., at 743–744. That remains true “even if the infor-
mation is revealed on the assumption that it will be used
only for a limited purpose.” United States v. Miller, 425
U. S. 435, 443 (1976). As a result, the Government is
typically free to obtain such information from the recipient
without triggering Fourth Amendment protections.
This third-party doctrine largely traces its roots to
Miller. While investigating Miller for tax evasion, the
Government subpoenaed his banks, seeking several
months of canceled checks, deposit slips, and monthly
statements. The Court rejected a Fourth Amendment
challenge to the records collection. For one, Miller could
“assert neither ownership nor possession” of the docu-
ments; they were “business records of the banks.” Id., at
440. For another, the nature of those records confirmed
Miller’s limited expectation of privacy, because the checks
were “not confidential communications but negotiable
instruments to be used in commercial transactions,” and
the bank statements contained information “exposed to
——————
2 JUSTICE KENNEDY argues that this case is in a different category
from Jones and the dragnet-type practices posited in Knotts because the
disclosure of the cell-site records was subject to “judicial authorization.”
Post, at 14–16. That line of argument conflates the threshold question
whether a “search” has occurred with the separate matter of whether
the search was reasonable. The subpoena process set forth in the
Stored Communications Act does not determine a target’s expectation
of privacy. And in any event, neither Jones nor Knotts purported to
resolve the question of what authorization may be required to conduct
such electronic surveillance techniques. But see Jones, 565 U. S., at
430 (ALITO, J., concurring in judgment) (indicating that longer term
GPS tracking may require a warrant).
10 CARPENTER v. UNITED STATES
Opinion of the Court
[bank] employees in the ordinary course of business.” Id.,
at 442. The Court thus concluded that Miller had “take[n]
the risk, in revealing his affairs to another, that the in-
formation [would] be conveyed by that person to the Gov-
ernment.” Id., at 443.
Three years later, Smith applied the same principles in
the context of information conveyed to a telephone com-
pany. The Court ruled that the Government’s use of a pen
register—a device that recorded the outgoing phone num-
bers dialed on a landline telephone—was not a search.
Noting the pen register’s “limited capabilities,” the Court
“doubt[ed] that people in general entertain any actual
expectation of privacy in the numbers they dial.” 442
U. S., at 742. Telephone subscribers know, after all, that
the numbers are used by the telephone company “for a
variety of legitimate business purposes,” including routing
calls. Id., at 743. And at any rate, the Court explained,
such an expectation “is not one that society is prepared to
recognize as reasonable.” Ibid. (internal quotation marks
omitted). When Smith placed a call, he “voluntarily con-
veyed” the dialed numbers to the phone company by “ex-
pos[ing] that information to its equipment in the ordinary
course of business.” Id., at 744 (internal quotation marks
omitted). Once again, we held that the defendant “as-
sumed the risk” that the company’s records “would be
divulged to police.” Id., at 745.
III
The question we confront today is how to apply the
Fourth Amendment to a new phenomenon: the ability to
chronicle a person’s past movements through the record of
his cell phone signals. Such tracking partakes of many of
the qualities of the GPS monitoring we considered in
Jones. Much like GPS tracking of a vehicle, cell phone
location information is detailed, encyclopedic, and effort-
lessly compiled.
Cite as: 585 U. S. ____ (2018) 11
Opinion of the Court
At the same time, the fact that the individual continu-
ously reveals his location to his wireless carrier implicates
the third-party principle of Smith and Miller. But while
the third-party doctrine applies to telephone numbers and
bank records, it is not clear whether its logic extends to
the qualitatively different category of cell-site records.
After all, when Smith was decided in 1979, few could have
imagined a society in which a phone goes wherever its
owner goes, conveying to the wireless carrier not just
dialed digits, but a detailed and comprehensive record of
the person’s movements.
We decline to extend Smith and Miller to cover these
novel circumstances. Given the unique nature of cell
phone location records, the fact that the information is
held by a third party does not by itself overcome the user’s
claim to Fourth Amendment protection. Whether the
Government employs its own surveillance technology as in
Jones or leverages the technology of a wireless carrier, we
hold that an individual maintains a legitimate expectation
of privacy in the record of his physical movements as
captured through CSLI. The location information ob-
tained from Carpenter’s wireless carriers was the product
of a search.3
——————
3 The parties suggest as an alternative to their primary submissions
that the acquisition of CSLI becomes a search only if it extends beyond
a limited period. See Reply Brief 12 (proposing a 24-hour cutoff); Brief
for United States 55–56 (suggesting a seven-day cutoff). As part of its
argument, the Government treats the seven days of CSLI requested
from Sprint as the pertinent period, even though Sprint produced only
two days of records. Brief for United States 56. Contrary to JUSTICE
KENNEDY’s assertion, post, at 19, we need not decide whether there is a
limited period for which the Government may obtain an individual’s
historical CSLI free from Fourth Amendment scrutiny, and if so, how
long that period might be. It is sufficient for our purposes today to hold
that accessing seven days of CSLI constitutes a Fourth Amendment
search.
12 CARPENTER v. UNITED STATES
Opinion of the Court
A
A person does not surrender all Fourth Amendment
protection by venturing into the public sphere. To the
contrary, “what [one] seeks to preserve as private, even in
an area accessible to the public, may be constitutionally
protected.” Katz, 389 U. S., at 351–352. A majority of this
Court has already recognized that individuals have a
reasonable expectation of privacy in the whole of their
physical movements. Jones, 565 U. S., at 430 (ALITO, J.,
concurring in judgment); id., at 415 (SOTOMAYOR, J.,
concurring). Prior to the digital age, law enforcement
might have pursued a suspect for a brief stretch, but doing
so “for any extended period of time was difficult and costly
and therefore rarely undertaken.” Id., at 429 (opinion of
ALITO, J.). For that reason, “society’s expectation has
been that law enforcement agents and others would not—
and indeed, in the main, simply could not—secretly moni-
tor and catalogue every single movement of an individual’s
car for a very long period.” Id., at 430.
Allowing government access to cell-site records contra-
venes that expectation. Although such records are gener-
ated for commercial purposes, that distinction does not
negate Carpenter’s anticipation of privacy in his physical
location. Mapping a cell phone’s location over the course
of 127 days provides an all-encompassing record of the
holder’s whereabouts. As with GPS information, the time-
stamped data provides an intimate window into a person’s
life, revealing not only his particular movements, but
through them his “familial, political, professional, reli-
gious, and sexual associations.” Id., at 415 (opinion of
SOTOMAYOR, J.). These location records “hold for many
Americans the ‘privacies of life.’ ” Riley, 573 U. S., at ___
(slip op., at 28) (quoting Boyd, 116 U. S., at 630). And like
GPS monitoring, cell phone tracking is remarkably easy,
cheap, and efficient compared to traditional investigative
tools. With just the click of a button, the Government can
Cite as: 585 U. S. ____ (2018) 13
Opinion of the Court
access each carrier’s deep repository of historical location
information at practically no expense.
In fact, historical cell-site records present even greater
privacy concerns than the GPS monitoring of a vehicle we
considered in Jones. Unlike the bugged container in
Knotts or the car in Jones, a cell phone—almost a “feature
of human anatomy,” Riley, 573 U. S., at ___ (slip op., at
9)—tracks nearly exactly the movements of its owner.
While individuals regularly leave their vehicles, they
compulsively carry cell phones with them all the time. A
cell phone faithfully follows its owner beyond public thor-
oughfares and into private residences, doctor’s offices,
political headquarters, and other potentially revealing
locales. See id., at ___ (slip op., at 19) (noting that “nearly
three-quarters of smart phone users report being within
five feet of their phones most of the time, with 12% admit-
ting that they even use their phones in the shower”);
contrast Cardwell v. Lewis, 417 U. S. 583, 590 (1974)
(plurality opinion) (“A car has little capacity for escaping
public scrutiny.”). Accordingly, when the Government
tracks the location of a cell phone it achieves near perfect
surveillance, as if it had attached an ankle monitor to the
phone’s user.
Moreover, the retrospective quality of the data here
gives police access to a category of information otherwise
unknowable. In the past, attempts to reconstruct a per-
son’s movements were limited by a dearth of records and
the frailties of recollection. With access to CSLI, the
Government can now travel back in time to retrace a
person’s whereabouts, subject only to the retention polices
of the wireless carriers, which currently maintain records
for up to five years. Critically, because location infor-
mation is continually logged for all of the 400 million
devices in the United States—not just those belonging to
persons who might happen to come under investigation—
this newfound tracking capacity runs against everyone.
14 CARPENTER v. UNITED STATES
Opinion of the Court
Unlike with the GPS device in Jones, police need not even
know in advance whether they want to follow a particular
individual, or when.
Whoever the suspect turns out to be, he has effectively
been tailed every moment of every day for five years, and
the police may—in the Government’s view—call upon the
results of that surveillance without regard to the con-
straints of the Fourth Amendment. Only the few with-
out cell phones could escape this tireless and absolute
surveillance.
The Government and JUSTICE KENNEDY contend, how-
ever, that the collection of CSLI should be permitted
because the data is less precise than GPS information.
Not to worry, they maintain, because the location records
did “not on their own suffice to place [Carpenter] at the
crime scene”; they placed him within a wedge-shaped
sector ranging from one-eighth to four square miles. Brief
for United States 24; see post, at 18–19. Yet the Court has
already rejected the proposition that “inference insulates a
search.” Kyllo, 533 U. S., at 36. From the 127 days of
location data it received, the Government could, in combi-
nation with other information, deduce a detailed log of
Carpenter’s movements, including when he was at the site
of the robberies. And the Government thought the CSLI
accurate enough to highlight it during the closing argu-
ment of his trial. App. 131.
At any rate, the rule the Court adopts “must take ac-
count of more sophisticated systems that are already in
use or in development.” Kyllo, 533 U. S., at 36. While the
records in this case reflect the state of technology at the
start of the decade, the accuracy of CSLI is rapidly ap-
proaching GPS-level precision. As the number of cell sites
has proliferated, the geographic area covered by each cell
sector has shrunk, particularly in urban areas. In addi-
tion, with new technology measuring the time and angle of
signals hitting their towers, wireless carriers already have
Cite as: 585 U. S. ____ (2018) 15
Opinion of the Court
the capability to pinpoint a phone’s location within 50
meters. Brief for Electronic Frontier Foundation et al. as
Amici Curiae 12 (describing triangulation methods that
estimate a device’s location inside a given cell sector).
Accordingly, when the Government accessed CSLI from
the wireless carriers, it invaded Carpenter’s reason-
able expectation of privacy in the whole of his physical
movements.
B
The Government’s primary contention to the contrary is
that the third-party doctrine governs this case. In its
view, cell-site records are fair game because they are
“business records” created and maintained by the wireless
carriers. The Government (along with JUSTICE KENNEDY)
recognizes that this case features new technology, but
asserts that the legal question nonetheless turns on a
garden-variety request for information from a third-party
witness. Brief for United States 32–34; post, at 12–14.
The Government’s position fails to contend with the
seismic shifts in digital technology that made possible the
tracking of not only Carpenter’s location but also everyone
else’s, not for a short period but for years and years.
Sprint Corporation and its competitors are not your typi-
cal witnesses. Unlike the nosy neighbor who keeps an eye
on comings and goings, they are ever alert, and their
memory is nearly infallible. There is a world of difference
between the limited types of personal information ad-
dressed in Smith and Miller and the exhaustive chronicle
of location information casually collected by wireless
carriers today. The Government thus is not asking for a
straightforward application of the third-party doctrine,
but instead a significant extension of it to a distinct cate-
gory of information.
The third-party doctrine partly stems from the notion
that an individual has a reduced expectation of privacy in
16 CARPENTER v. UNITED STATES
Opinion of the Court
information knowingly shared with another. But the fact
of “diminished privacy interests does not mean that the
Fourth Amendment falls out of the picture entirely.”
Riley, 573 U. S., at ___ (slip op., at 16). Smith and Miller,
after all, did not rely solely on the act of sharing. Instead,
they considered “the nature of the particular documents
sought” to determine whether “there is a legitimate ‘expec-
tation of privacy’ concerning their contents.” Miller, 425
U. S., at 442. Smith pointed out the limited capabilities of
a pen register; as explained in Riley, telephone call logs
reveal little in the way of “identifying information.”
Smith, 442 U. S., at 742; Riley, 573 U. S., at ___ (slip op.,
at 24). Miller likewise noted that checks were “not confi-
dential communications but negotiable instruments to be
used in commercial transactions.” 425 U. S., at 442. In
mechanically applying the third-party doctrine to this
case, the Government fails to appreciate that there are no
comparable limitations on the revealing nature of CSLI.
The Court has in fact already shown special solicitude
for location information in the third-party context. In
Knotts, the Court relied on Smith to hold that an individ-
ual has no reasonable expectation of privacy in public
movements that he “voluntarily conveyed to anyone who
wanted to look.” Knotts, 460 U. S., at 281; see id., at 283
(discussing Smith). But when confronted with more per-
vasive tracking, five Justices agreed that longer term GPS
monitoring of even a vehicle traveling on public streets
constitutes a search. Jones, 565 U. S., at 430 (ALITO, J.,
concurring in judgment); id., at 415 (SOTOMAYOR, J.,
concurring). JUSTICE GORSUCH wonders why “someone’s
location when using a phone” is sensitive, post, at 3, and
JUSTICE KENNEDY assumes that a person’s discrete
movements “are not particularly private,” post, at 17. Yet
this case is not about “using a phone” or a person’s move-
ment at a particular time. It is about a detailed chronicle
of a person’s physical presence compiled every day, every
Cite as: 585 U. S. ____ (2018) 17
Opinion of the Court
moment, over several years. Such a chronicle implicates
privacy concerns far beyond those considered in Smith and
Miller.
Neither does the second rationale underlying the third-
party doctrine—voluntary exposure—hold up when it
comes to CSLI. Cell phone location information is not
truly “shared” as one normally understands the term. In
the first place, cell phones and the services they provide
are “such a pervasive and insistent part of daily life” that
carrying one is indispensable to participation in modern
society. Riley, 573 U. S., at ___ (slip op., at 9). Second, a
cell phone logs a cell-site record by dint of its operation,
without any affirmative act on the part of the user beyond
powering up. Virtually any activity on the phone gener-
ates CSLI, including incoming calls, texts, or e-mails and
countless other data connections that a phone automati-
cally makes when checking for news, weather, or social
media updates. Apart from disconnecting the phone from
the network, there is no way to avoid leaving behind a
trail of location data. As a result, in no meaningful sense
does the user voluntarily “assume[ ] the risk” of turning
over a comprehensive dossier of his physical movements.
Smith, 442 U. S., at 745.
We therefore decline to extend Smith and Miller to the
collection of CSLI. Given the unique nature of cell phone
location information, the fact that the Government ob-
tained the information from a third party does not over-
come Carpenter’s claim to Fourth Amendment protection.
The Government’s acquisition of the cell-site records was a
search within the meaning of the Fourth Amendment.
* * *
Our decision today is a narrow one. We do not express a
view on matters not before us: real-time CSLI or “tower
dumps” (a download of information on all the devices that
connected to a particular cell site during a particular
18 CARPENTER v. UNITED STATES
Opinion of the Court
interval). We do not disturb the application of Smith and
Miller or call into question conventional surveillance
techniques and tools, such as security cameras. Nor do we
address other business records that might incidentally
reveal location information. Further, our opinion does not
consider other collection techniques involving foreign
affairs or national security. As Justice Frankfurter noted
when considering new innovations in airplanes and radios,
the Court must tread carefully in such cases, to ensure
that we do not “embarrass the future.” Northwest Air-
lines, Inc. v. Minnesota, 322 U. S. 292, 300 (1944).4
IV
Having found that the acquisition of Carpenter’s CSLI
was a search, we also conclude that the Government must
generally obtain a warrant supported by probable cause
before acquiring such records. Although the “ultimate
measure of the constitutionality of a governmental search
is ‘reasonableness,’ ” our cases establish that warrantless
searches are typically unreasonable where “a search is
undertaken by law enforcement officials to discover evi-
dence of criminal wrongdoing.” Vernonia School Dist. 47J
v. Acton, 515 U. S. 646, 652–653 (1995). Thus, “[i]n the
absence of a warrant, a search is reasonable only if it falls
within a specific exception to the warrant requirement.”
Riley, 573 U. S., at ___ (slip op., at 5).
The Government acquired the cell-site records pursuant
to a court order issued under the Stored Communications
Act, which required the Government to show “reasonable
grounds” for believing that the records were “relevant and
——————
4 JUSTICE GORSUCH faults us for not promulgating a complete code
addressing the manifold situations that may be presented by this new
technology—under a constitutional provision turning on what is “rea-
sonable,” no less. Post, at 10–12. Like JUSTICE GORSUCH, we “do not
begin to claim all the answers today,” post, at 13, and therefore decide
no more than the case before us.
Cite as: 585 U. S. ____ (2018) 19
Opinion of the Court
material to an ongoing investigation.” 18 U. S. C.
§2703(d). That showing falls well short of the probable
cause required for a warrant. The Court usually requires
“some quantum of individualized suspicion” before
a search or seizure may take place. United States v.
Martinez-Fuerte, 428 U. S. 543, 560–561 (1976). Under the
standard in the Stored Communications Act, however, law
enforcement need only show that the cell-site evidence
might be pertinent to an ongoing investigation—a “gigan-
tic” departure from the probable cause rule, as the Gov-
ernment explained below. App. 34. Consequently, an
order issued under Section 2703(d) of the Act is not a
permissible mechanism for accessing historical cell-site
records. Before compelling a wireless carrier to turn over
a subscriber’s CSLI, the Government’s obligation is a
familiar one—get a warrant.
JUSTICE ALITO contends that the warrant requirement
simply does not apply when the Government acquires
records using compulsory process. Unlike an actual
search, he says, subpoenas for documents do not involve
the direct taking of evidence; they are at most a “construc-
tive search” conducted by the target of the subpoena. Post,
at 12. Given this lesser intrusion on personal privacy,
JUSTICE ALITO argues that the compulsory production of
records is not held to the same probable cause standard.
In his view, this Court’s precedents set forth a categorical
rule—separate and distinct from the third-party doc-
trine—subjecting subpoenas to lenient scrutiny without
regard to the suspect’s expectation of privacy in the rec-
ords. Post, at 8–19.
But this Court has never held that the Government may
subpoena third parties for records in which the suspect
has a reasonable expectation of privacy. Almost all of the
examples JUSTICE ALITO cites, see post, at 14–15, contem-
plated requests for evidence implicating diminished pri-
20 CARPENTER v. UNITED STATES
Opinion of the Court
vacy interests or for a corporation’s own books.5 The lone
exception, of course, is Miller, where the Court’s analysis
of the third-party subpoena merged with the application of
the third-party doctrine. 425 U. S., at 444 (concluding
that Miller lacked the necessary privacy interest to contest
the issuance of a subpoena to his bank).
JUSTICE ALITO overlooks the critical issue. At some
point, the dissent should recognize that CSLI is an entirely
different species of business record—something that
implicates basic Fourth Amendment concerns about arbi-
trary government power much more directly than corpo-
rate tax or payroll ledgers. When confronting new con-
cerns wrought by digital technology, this Court has been
careful not to uncritically extend existing precedents. See
Riley, 573 U. S., at ___ (slip op., at 10) (“A search of
the information on a cell phone bears little resemblance
to the type of brief physical search considered [in prior
precedents].”).
If the choice to proceed by subpoena provided a categori-
cal limitation on Fourth Amendment protection, no type of
record would ever be protected by the warrant require-
ment. Under JUSTICE ALITO’s view, private letters, digital
contents of a cell phone—any personal information re-
duced to document form, in fact—may be collected by
——————
5 See United States v. Dionisio, 410 U. S. 1, 14 (1973) (“No person can
have a reasonable expectation that others will not know the sound of
his voice”); Donovan v. Lone Steer, Inc., 464 U. S. 408, 411, 415 (1984)
(payroll and sales records); California Bankers Assn. v. Shultz, 416
U. S. 21, 67 (1974) (Bank Secrecy Act reporting requirements); See v.
Seattle, 387 U. S. 541, 544 (1967) (financial books and records); United
States v. Powell, 379 U. S. 48, 49, 57 (1964) (corporate tax records);
McPhaul v. United States, 364 U. S. 372, 374, 382 (1960) (books and
records of an organization); United States v. Morton Salt Co., 338 U. S.
632, 634, 651–653 (1950) (Federal Trade Commission reporting re-
quirement); Oklahoma Press Publishing Co. v. Walling, 327 U. S. 186,
189, 204–208 (1946) (payroll records); Hale v. Henkel, 201 U. S. 43, 45,
75 (1906) (corporate books and papers).
Cite as: 585 U. S. ____ (2018) 21
Opinion of the Court
subpoena for no reason other than “official curiosity.”
United States v. Morton Salt Co., 338 U. S. 632, 652
(1950). JUSTICE KENNEDY declines to adopt the radical
implications of this theory, leaving open the question
whether the warrant requirement applies “when the Gov-
ernment obtains the modern-day equivalents of an indi-
vidual’s own ‘papers’ or ‘effects,’ even when those papers
or effects are held by a third party. ” Post, at 13 (citing
United States v. Warshak, 631 F. 3d 266, 283–288 (CA6
2010)). That would be a sensible exception, because it
would prevent the subpoena doctrine from overcoming any
reasonable expectation of privacy. If the third-party doc-
trine does not apply to the “modern-day equivalents of an
individual’s own ‘papers’ or ‘effects,’ ” then the clear impli-
cation is that the documents should receive full Fourth
Amendment protection. We simply think that such pro-
tection should extend as well to a detailed log of a person’s
movements over several years.
This is certainly not to say that all orders compelling the
production of documents will require a showing of proba-
ble cause. The Government will be able to use subpoenas
to acquire records in the overwhelming majority of inves-
tigations. We hold only that a warrant is required in the
rare case where the suspect has a legitimate privacy in-
terest in records held by a third party.
Further, even though the Government will generally
need a warrant to access CSLI, case-specific exceptions
may support a warrantless search of an individual’s cell-
site records under certain circumstances. “One well-
recognized exception applies when ‘ “the exigencies of the
situation” make the needs of law enforcement so compel-
ling that [a] warrantless search is objectively reasonable
under the Fourth Amendment.’ ” Kentucky v. King, 563
U. S. 452, 460 (2011) (quoting Mincey v. Arizona, 437 U. S.
385, 394 (1978)). Such exigencies include the need to
pursue a fleeing suspect, protect individuals who are
22 CARPENTER v. UNITED STATES
Opinion of the Court
threatened with imminent harm, or prevent the imminent
destruction of evidence. 563 U. S., at 460, and n. 3.
As a result, if law enforcement is confronted with an
urgent situation, such fact-specific threats will likely
justify the warrantless collection of CSLI. Lower courts,
for instance, have approved warrantless searches related
to bomb threats, active shootings, and child abductions.
Our decision today does not call into doubt warrantless
access to CSLI in such circumstances. While police must
get a warrant when collecting CSLI to assist in the mine-
run criminal investigation, the rule we set forth does not
limit their ability to respond to an ongoing emergency.
* * *
As Justice Brandeis explained in his famous dissent, the
Court is obligated—as “[s]ubtler and more far-reaching
means of invading privacy have become available to the
Government”—to ensure that the “progress of science”
does not erode Fourth Amendment protections. Olmstead
v. United States, 277 U. S. 438, 473–474 (1928). Here the
progress of science has afforded law enforcement a power-
ful new tool to carry out its important responsibilities. At
the same time, this tool risks Government encroachment
of the sort the Framers, “after consulting the lessons of
history,” drafted the Fourth Amendment to prevent. Di
Re, 332 U. S., at 595.
We decline to grant the state unrestricted access to a
wireless carrier’s database of physical location infor-
mation. In light of the deeply revealing nature of CSLI,
its depth, breadth, and comprehensive reach, and the
inescapable and automatic nature of its collection, the fact
that such information is gathered by a third party does not
make it any less deserving of Fourth Amendment protec-
tion. The Government’s acquisition of the cell-site records
here was a search under that Amendment.
The judgment of the Court of Appeals is reversed, and
Cite as: 585 U. S. ____ (2018) 23
Opinion of the Court
the case is remanded for further proceedings consistent
with this opinion.
It is so ordered.
Cite as: 585 U. S. ____ (2018) 1
KENNEDY, J., dissenting
SUPREME COURT OF THE UNITED STATES
_________________
No. 16–402
_________________
TIMOTHY IVORY CARPENTER, PETITIONER v.
UNITED STATES
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE SIXTH CIRCUIT
[June 22, 2018]
JUSTICE KENNEDY, with whom JUSTICE THOMAS and
JUSTICE ALITO join, dissenting.
This case involves new technology, but the Court’s stark
departure from relevant Fourth Amendment precedents
and principles is, in my submission, unnecessary and
incorrect, requiring this respectful dissent.
The new rule the Court seems to formulate puts needed,
reasonable, accepted, lawful, and congressionally author-
ized criminal investigations at serious risk in serious
cases, often when law enforcement seeks to prevent the
threat of violent crimes. And it places undue restrictions
on the lawful and necessary enforcement powers exercised
not only by the Federal Government, but also by law
enforcement in every State and locality throughout the
Nation. Adherence to this Court’s longstanding prece-
dents and analytic framework would have been the proper
and prudent way to resolve this case.
The Court has twice held that individuals have no
Fourth Amendment interests in business records which
are possessed, owned, and controlled by a third party.
United States v. Miller, 425 U. S. 435 (1976); Smith v.
Maryland, 442 U. S. 735 (1979). This is true even when
the records contain personal and sensitive information. So
when the Government uses a subpoena to obtain, for
example, bank records, telephone records, and credit card
2 CARPENTER v. UNITED STATES
KENNEDY, J., dissenting
statements from the businesses that create and keep these
records, the Government does not engage in a search of
the business’s customers within the meaning of the Fourth
Amendment.
In this case petitioner challenges the Government’s
right to use compulsory process to obtain a now-common
kind of business record: cell-site records held by cell phone
service providers. The Government acquired the records
through an investigative process enacted by Congress.
Upon approval by a neutral magistrate, and based on the
Government’s duty to show reasonable necessity, it au-
thorizes the disclosure of records and information that are
under the control and ownership of the cell phone service
provider, not its customer. Petitioner acknowledges that
the Government may obtain a wide variety of business
records using compulsory process, and he does not ask the
Court to revisit its precedents. Yet he argues that, under
those same precedents, the Government searched his
records when it used court-approved compulsory process to
obtain the cell-site information at issue here.
Cell-site records, however, are no different from the
many other kinds of business records the Government has
a lawful right to obtain by compulsory process. Customers
like petitioner do not own, possess, control, or use the
records, and for that reason have no reasonable expecta-
tion that they cannot be disclosed pursuant to lawful
compulsory process.
The Court today disagrees. It holds for the first time
that by using compulsory process to obtain records of a
business entity, the Government has not just engaged in
an impermissible action, but has conducted a search of the
business’s customer. The Court further concludes that the
search in this case was unreasonable and the Government
needed to get a warrant to obtain more than six days of
cell-site records.
In concluding that the Government engaged in a search,
Cite as: 585 U. S. ____ (2018) 3
KENNEDY, J., dissenting
the Court unhinges Fourth Amendment doctrine from the
property-based concepts that have long grounded the
analytic framework that pertains in these cases. In doing
so it draws an unprincipled and unworkable line between
cell-site records on the one hand and financial and tele-
phonic records on the other. According to today’s majority
opinion, the Government can acquire a record of every
credit card purchase and phone call a person makes over
months or years without upsetting a legitimate expecta-
tion of privacy. But, in the Court’s view, the Government
crosses a constitutional line when it obtains a court’s
approval to issue a subpoena for more than six days of
cell-site records in order to determine whether a person
was within several hundred city blocks of a crime scene.
That distinction is illogical and will frustrate principled
application of the Fourth Amendment in many routine yet
vital law enforcement operations.
It is true that the Cyber Age has vast potential both to
expand and restrict individual freedoms in dimensions not
contemplated in earlier times. See Packingham v. North
Carolina, 582 U. S. ___, ___–___ (2017) (slip op., at 46).
For the reasons that follow, however, there is simply no
basis here for concluding that the Government interfered
with information that the cell phone customer, either from
a legal or commonsense standpoint, should have thought
the law would deem owned or controlled by him.
I
Before evaluating the question presented it is helpful to
understand the nature of cell-site records, how they are
commonly used by cell phone service providers, and their
proper use by law enforcement.
When a cell phone user makes a call, sends a text mes-
sage or e-mail, or gains access to the Internet, the cell
phone establishes a radio connection to an antenna at a
nearby cell site. The typical cell site covers a more-or-less
4 CARPENTER v. UNITED STATES
KENNEDY, J., dissenting
circular geographic area around the site. It has three (or
sometimes six) separate antennas pointing in different
directions. Each provides cell service for a different 120-
degree (or 60-degree) sector of the cell site’s circular cover-
age area. So a cell phone activated on the north side of a
cell site will connect to a different antenna than a cell
phone on the south side.
Cell phone service providers create records each time a
cell phone connects to an antenna at a cell site. For a
phone call, for example, the provider records the date,
time, and duration of the call; the phone numbers making
and receiving the call; and, most relevant here, the cell
site used to make the call, as well as the specific antenna
that made the connection. The cell-site and antenna data
points, together with the date and time of connection, are
known as cell-site location information, or cell-site records.
By linking an individual’s cell phone to a particular 120-
or 60-degree sector of a cell site’s coverage area at a par-
ticular time, cell-site records reveal the general location of
the cell phone user.
The location information revealed by cell-site records is
imprecise, because an individual cell-site sector usually
covers a large geographic area. The FBI agent who offered
expert testimony about the cell-site records at issue here
testified that a cell site in a city reaches between a half
mile and two miles in all directions. That means a 60-
degree sector covers between approximately one-eighth
and two square miles (and a 120-degree sector twice that
area). To put that in perspective, in urban areas cell-site
records often would reveal the location of a cell phone user
within an area covering between around a dozen and
several hundred city blocks. In rural areas cell-site rec-
ords can be up to 40 times more imprecise. By contrast, a
Global Positioning System (GPS) can reveal an individ-
ual’s location within around 15 feet.
Major cell phone service providers keep cell-site records
Cite as: 585 U. S. ____ (2018) 5
KENNEDY, J., dissenting
for long periods of time. There is no law requiring them to
do so. Instead, providers contract with their customers to
collect and keep these records because they are valuable to
the providers. Among other things, providers aggregate
the records and sell them to third parties along with other
information gleaned from cell phone usage. This data can
be used, for example, to help a department store deter-
mine which of various prospective store locations is likely
to get more foot traffic from middle-aged women who live
in affluent zip codes. The market for cell phone data is
now estimated to be in the billions of dollars. See Brief for
Technology Experts as Amici Curiae 23.
Cell-site records also can serve an important investiga-
tive function, as the facts of this case demonstrate. Peti-
tioner, Timothy Carpenter, along with a rotating group of
accomplices, robbed at least six RadioShack and T-Mobile
stores at gunpoint over a 2-year period. Five of those
robberies occurred in the Detroit area, each crime at least
four miles from the last. The sixth took place in Warren,
Ohio, over 200 miles from Detroit.
The Government, of course, did not know all of these
details in 2011 when it began investigating Carpenter. In
April of that year police arrested four of Carpenter’s co-
conspirators. One of them confessed to committing nine
robberies in Michigan and Ohio between December 2010
and March 2011. He identified 15 accomplices who had
participated in at least one of those robberies; named
Carpenter as one of the accomplices; and provided Carpen-
ter’s cell phone number to the authorities. The suspect
also warned that the other members of the conspiracy
planned to commit more armed robberies in the immediate
future.
The Government at this point faced a daunting task.
Even if it could identify and apprehend the suspects, still
it had to link each suspect in this changing criminal gang
to specific robberies in order to bring charges and convict.
6 CARPENTER v. UNITED STATES
KENNEDY, J., dissenting
And, of course, it was urgent that the Government take all
necessary steps to stop the ongoing and dangerous crime
spree.
Cell-site records were uniquely suited to this task. The
geographic dispersion of the robberies meant that, if Car-
penter’s cell phone were within even a dozen to several
hundred city blocks of one or more of the stores when the
different robberies occurred, there would be powerful
circumstantial evidence of his participation; and this
would be especially so if his cell phone usually was not
located in the sectors near the stores except during the
robbery times.
To obtain these records, the Government applied to
federal magistrate judges for disclosure orders pursuant to
§2703(d) of the Stored Communications Act. That Act
authorizes a magistrate judge to issue an order requiring
disclosure of cell-site records if the Government demon-
strates “specific and articulable facts showing that there
are reasonable grounds to believe” the records “are rele-
vant and material to an ongoing criminal investigation.”
18 U. S. C. §§2703(d), 2711(3). The full statutory provi-
sion is set out in the Appendix, infra.
From Carpenter’s primary service provider, MetroPCS,
the Government obtained records from between December
2010 and April 2011, based on its understanding that nine
robberies had occurred in that timeframe. The Govern-
ment also requested seven days of cell-site records from
Sprint, spanning the time around the robbery in Warren,
Ohio. It obtained two days of records.
These records confirmed that Carpenter’s cell phone was
in the general vicinity of four of the nine robberies, includ-
ing the one in Ohio, at the times those robberies occurred.
II
The first Clause of the Fourth Amendment provides that
“the right of the people to be secure in their persons, houses,
Cite as: 585 U. S. ____ (2018) 7
KENNEDY, J., dissenting
papers, and effects, against unreasonable searches and
seizures, shall not be violated.” The customary beginning
point in any Fourth Amendment search case is whether
the Government’s actions constitute a “search” of the
defendant’s person, house, papers, or effects, within the
meaning of the constitutional provision. If so, the next
question is whether that search was reasonable.
Here the only question necessary to decide is whether
the Government searched anything of Carpenter’s when it
used compulsory process to obtain cell-site records from
Carpenter’s cell phone service providers. This Court’s
decisions in Miller and Smith dictate that the answer is
no, as every Court of Appeals to have considered the ques-
tion has recognized. See United States v. Thompson, 866
F. 3d 1149 (CA10 2017); United States v. Graham, 824
F. 3d 421 (CA4 2016) (en banc); Carpenter v. United
States, 819 F. 3d 880 (CA6 2016); United States v. Davis,
785 F. 3d 498 (CA11 2015) (en banc); In re Application
of U. S. for Historical Cell Site Data, 724 F. 3d 600
(CA5 2013).
A
Miller and Smith hold that individuals lack any protected
Fourth Amendment interests in records that are pos-
sessed, owned, and controlled only by a third party. In
Miller federal law enforcement officers obtained four
months of the defendant’s banking records. 425 U. S., at
437438. And in Smith state police obtained records of
the phone numbers dialed from the defendant’s home
phone. 442 U. S., at 737. The Court held in both cases
that the officers did not search anything belonging to the
defendants within the meaning of the Fourth Amendment.
The defendants could “assert neither ownership nor pos-
session” of the records because the records were created,
owned, and controlled by the companies. Miller, supra, at
440; see Smith, supra, at 741. And the defendants had no
8 CARPENTER v. UNITED STATES
KENNEDY, J., dissenting
reasonable expectation of privacy in information they
“voluntarily conveyed to the [companies] and exposed to
their employees in the ordinary course of business.” Mil-
ler, supra, at 442; see Smith, 442 U. S., at 744. Rather,
the defendants “assumed the risk that the information
would be divulged to police.” Id., at 745.
Miller and Smith have been criticized as being based on
too narrow a view of reasonable expectations of privacy.
See, e.g., Ashdown, The Fourth Amendment and the “Le-
gitimate Expectation of Privacy,” 34 Vand. L. Rev. 1289,
13131316 (1981). Those criticisms, however, are unwar-
ranted. The principle established in Miller and Smith is
correct for two reasons, the first relating to a defendant’s
attenuated interest in property owned by another, and the
second relating to the safeguards inherent in the use of
compulsory process.
First, Miller and Smith placed necessary limits on the
ability of individuals to assert Fourth Amendment inter-
ests in property to which they lack a “requisite connec-
tion.” Minnesota v. Carter, 525 U. S. 83, 99 (1998)
(KENNEDY, J., concurring). Fourth Amendment rights,
after all, are personal. The Amendment protects “[t]he
right of the people to be secure in their . . . persons, houses,
papers, and effects”—not the persons, houses, papers, and
effects of others. (Emphasis added.)
The concept of reasonable expectations of privacy, first
announced in Katz v. United States, 389 U. S. 347 (1967),
sought to look beyond the “arcane distinctions developed
in property and tort law” in evaluating whether a person
has a sufficient connection to the thing or place searched
to assert Fourth Amendment interests in it. Rakas v.
Illinois, 439 U. S. 128, 143 (1978). Yet “property concepts”
are, nonetheless, fundamental “in determining the pres-
ence or absence of the privacy interests protected by that
Amendment.” Id., at 143144, n. 12. This is so for at least
two reasons. First, as a matter of settled expectations
Cite as: 585 U. S. ____ (2018) 9
KENNEDY, J., dissenting
from the law of property, individuals often have greater
expectations of privacy in things and places that belong to
them, not to others. And second, the Fourth Amendment’s
protections must remain tethered to the text of that
Amendment, which, again, protects only a person’s own
“persons, houses, papers, and effects.”
Katz did not abandon reliance on property-based con-
cepts. The Court in Katz analogized the phone booth used
in that case to a friend’s apartment, a taxicab, and a hotel
room. 389 U. S., at 352, 359. So when the defendant
“shu[t] the door behind him” and “pa[id] the toll,” id., at
352, he had a temporary interest in the space and a legit-
imate expectation that others would not intrude, much
like the interest a hotel guest has in a hotel room, Stoner
v. California, 376 U. S. 483 (1964), or an overnight guest
has in a host’s home, Minnesota v. Olson, 495 U. S. 91
(1990). The Government intruded on that space when it
attached a listening device to the phone booth. Katz, 389
U. S., at 348. (And even so, the Court made it clear that
the Government’s search could have been reasonable had
there been judicial approval on a case-specific basis,
which, of course, did occur here. Id., at 357359.)
Miller and Smith set forth an important and necessary
limitation on the Katz framework. They rest upon the
commonsense principle that the absence of property law
analogues can be dispositive of privacy expectations. The
defendants in those cases could expect that the third-party
businesses could use the records the companies collected,
stored, and classified as their own for any number of
business and commercial purposes. The businesses were
not bailees or custodians of the records, with a duty to
hold the records for the defendants’ use. The defendants
could make no argument that the records were their own
papers or effects. See Miller, supra, at 440 (“the docu-
ments subpoenaed here are not respondent’s ‘private
papers’ ”); Smith, supra, at 741 (“petitioner obviously
10 CARPENTER v. UNITED STATES
KENNEDY, J., dissenting
cannot claim that his ‘property’ was invaded”). The rec-
ords were the business entities’ records, plain and simple.
The defendants had no reason to believe the records were
owned or controlled by them and so could not assert a
reasonable expectation of privacy in the records.
The second principle supporting Miller and Smith is the
longstanding rule that the Government may use compul-
sory process to compel persons to disclose documents and
other evidence within their possession and control. See
United States v. Nixon, 418 U. S. 683, 709 (1974) (it is an
“ancient proposition of law” that “the public has a right to
every man’s evidence” (internal quotation marks and
alterations omitted)). A subpoena is different from a
warrant in its force and intrusive power. While a warrant
allows the Government to enter and seize and make the
examination itself, a subpoena simply requires the person
to whom it is directed to make the disclosure. A subpoena,
moreover, provides the recipient the “opportunity to pre-
sent objections” before complying, which further mitigates
the intrusion. Oklahoma Press Publishing Co. v. Walling,
327 U. S. 186, 195 (1946).
For those reasons this Court has held that a subpoena
for records, although a “constructive” search subject to
Fourth Amendment constraints, need not comply with the
procedures applicable to warrants—even when challenged
by the person to whom the records belong. Id., at 202,
208. Rather, a subpoena complies with the Fourth
Amendment’s reasonableness requirement so long as it is
“ ‘sufficiently limited in scope, relevant in purpose, and
specific in directive so that compliance will not be unrea-
sonably burdensome.’ ” Donovan v. Lone Steer, Inc., 464
U. S. 408, 415 (1984). Persons with no meaningful inter-
ests in the records sought by a subpoena, like the defend-
ants in Miller and Smith, have no rights to object to the
records’ disclosure—much less to assert that the Govern-
ment must obtain a warrant to compel disclosure of the
Cite as: 585 U. S. ____ (2018) 11
KENNEDY, J., dissenting
records. See Miller, 425 U. S., at 444446; SEC v. Jerry T.
O’Brien, Inc., 467 U. S. 735, 742743 (1984).
Based on Miller and Smith and the principles underly-
ing those cases, it is well established that subpoenas may
be used to obtain a wide variety of records held by busi-
nesses, even when the records contain private information.
See 2 W. LaFave, Search and Seizure §4.13 (5th ed. 2012).
Credit cards are a prime example. State and federal law
enforcement, for instance, often subpoena credit card
statements to develop probable cause to prosecute crimes
ranging from drug trafficking and distribution to
healthcare fraud to tax evasion. See United States v.
Phibbs, 999 F. 2d 1053 (CA6 1993) (drug distribution);
McCune v. DOJ, 592 Fed. Appx. 287 (CA5 2014)
(healthcare fraud); United States v. Green, 305 F. 3d 422
(CA6 2002) (drug trafficking and tax evasion); see also 12
U. S. C. §§3402(4), 3407 (allowing the Government to
subpoena financial records if “there is reason to believe
that the records sought are relevant to a legitimate law
enforcement inquiry”). Subpoenas also may be used to
obtain vehicle registration records, hotel records, employ-
ment records, and records of utility usage, to name just a
few other examples. See 1 LaFave, supra, §2.7(c).
And law enforcement officers are not alone in their
reliance on subpoenas to obtain business records for legit-
imate investigations. Subpoenas also are used for investi-
gatory purposes by state and federal grand juries, see
United States v. Dionisio, 410 U. S. 1 (1973), state and
federal administrative agencies, see Oklahoma Press,
supra, and state and federal legislative bodies, see
McPhaul v. United States, 364 U. S. 372 (1960).
B
Carpenter does not question these traditional investiga-
tive practices. And he does not ask the Court to reconsider
Miller and Smith. Carpenter argues only that, under
12 CARPENTER v. UNITED STATES
KENNEDY, J., dissenting
Miller and Smith, the Government may not use compulsory
process to acquire cell-site records from cell phone service
providers.
There is no merit in this argument. Cell-site records,
like all the examples just discussed, are created, kept,
classified, owned, and controlled by cell phone service
providers, which aggregate and sell this information to
third parties. As in Miller, Carpenter can “assert neither
ownership nor possession” of the records and has no con-
trol over them. 425 U. S., at 440.
Carpenter argues that he has Fourth Amendment inter-
ests in the cell-site records because they are in essence his
personal papers by operation of 47 U. S. C. §222. That
statute imposes certain restrictions on how providers may
use “customer proprietary network information”—a term
that encompasses cell-site records. §§222(c), (h)(1)(A).
The statute in general prohibits providers from disclosing
personally identifiable cell-site records to private third
parties. §222(c)(1). And it allows customers to request
cell-site records from the provider. §222(c)(2).
Carpenter’s argument is unpersuasive, however, for
§222 does not grant cell phone customers any meaningful
interest in cell-site records. The statute’s confidentiality
protections may be overridden by the interests of the
providers or the Government. The providers may disclose
the records “to protect the[ir] rights or property” or to
“initiate, render, bill, and collect for telecommunications
services.” §§222(d)(1), (2). They also may disclose the
records “as required by law”—which, of course, is how they
were disclosed in this case. §222(c)(1). Nor does the stat-
ute provide customers any practical control over the rec-
ords. Customers do not create the records; they have no
say in whether or for how long the records are stored; and
they cannot require the records to be modified or de-
stroyed. Even their right to request access to the records
is limited, for the statute “does not preclude a carrier from
Cite as: 585 U. S. ____ (2018) 13
KENNEDY, J., dissenting
being reimbursed by the customers . . . for the costs asso-
ciated with making such disclosures.” H. R. Rep. No. 104–
204, pt. 1, p. 90 (1995). So in every legal and practical
sense the “network information” regulated by §222 is,
under that statute, “proprietary” to the service providers,
not Carpenter. The Court does not argue otherwise.
Because Carpenter lacks a requisite connection to the
cell-site records, he also may not claim a reasonable expec-
tation of privacy in them. He could expect that a third
party—the cell phone service provider—could use the
information it collected, stored, and classified as its own
for a variety of business and commercial purposes.
All this is not to say that Miller and Smith are without
limits. Miller and Smith may not apply when the Gov-
ernment obtains the modern-day equivalents of an indi-
vidual’s own “papers” or “effects,” even when those papers
or effects are held by a third party. See Ex parte Jackson,
96 U. S. 727, 733 (1878) (letters held by mail carrier);
United States v. Warshak, 631 F. 3d 266, 283288 (CA6
2010) (e-mails held by Internet service provider). As
already discussed, however, this case does not involve
property or a bailment of that sort. Here the Govern-
ment’s acquisition of cell-site records falls within the
heartland of Miller and Smith.
In fact, Carpenter’s Fourth Amendment objection is
even weaker than those of the defendants in Miller and
Smith. Here the Government did not use a mere sub-
poena to obtain the cell-site records. It acquired the records
only after it proved to a Magistrate Judge reasonable
grounds to believe that the records were relevant and
material to an ongoing criminal investigation. See 18
U. S. C. §2703(d). So even if §222 gave Carpenter some
attenuated interest in the records, the Government’s
conduct here would be reasonable under the standards
governing subpoenas. See Donovan, 464 U. S., at 415.
Under Miller and Smith, then, a search of the sort that
14 CARPENTER v. UNITED STATES
KENNEDY, J., dissenting
requires a warrant simply did not occur when the Gov-
ernment used court-approved compulsory process, based
on a finding of reasonable necessity, to compel a cell phone
service provider, as owner, to disclose cell-site records.
III
The Court rejects a straightforward application of Miller
and Smith. It concludes instead that applying those cases
to cell-site records would work a “significant extension” of
the principles underlying them, ante, at 15, and holds that
the acquisition of more than six days of cell-site records
constitutes a search, ante, at 11, n. 3.
In my respectful view the majority opinion misreads this
Court’s precedents, old and recent, and transforms Miller
and Smith into an unprincipled and unworkable doctrine.
The Court’s newly conceived constitutional standard will
cause confusion; will undermine traditional and important
law enforcement practices; and will allow the cell phone to
become a protected medium that dangerous persons will
use to commit serious crimes.
A
The Court errs at the outset by attempting to sidestep
Miller and Smith. The Court frames this case as following
instead from United States v. Knotts, 460 U. S. 276 (1983),
and United States v. Jones, 565 U. S. 400 (2012). Those
cases, the Court suggests, establish that “individuals have
a reasonable expectation of privacy in the whole of their
physical movements.” Ante, at 79, 12.
Knotts held just the opposite: “A person traveling in an
automobile on public thoroughfares has no reasonable
expectation of privacy in his movements from one place to
another.” 460 U. S., at 281. True, the Court in Knotts also
suggested that “different constitutional principles may be
applicable” to “dragnet-type law enforcement practices.”
Id., at 284. But by dragnet practices the Court was refer-
Cite as: 585 U. S. ____ (2018) 15
KENNEDY, J., dissenting
ring to “ ‘twenty-four hour surveillance of any citizen of
this country . . . without judicial knowledge or supervi-
sion.’ ” Id., at 283.
Those “different constitutional principles” mentioned in
Knotts, whatever they may be, do not apply in this case.
Here the Stored Communications Act requires a neutral
judicial officer to confirm in each case that the Govern-
ment has “reasonable grounds to believe” the cell-site
records “are relevant and material to an ongoing criminal
investigation.” 18 U. S. C. §2703(d). This judicial check
mitigates the Court’s concerns about “ ‘a too permeating
police surveillance.’ ” Ante, at 6 (quoting United States v.
Di Re, 332 U. S. 581, 595 (1948)). Here, even more so
than in Knotts, “reality hardly suggests abuse.” 460 U. S.,
at 284.
The Court’s reliance on Jones fares no better. In Jones
the Government installed a GPS tracking device on the
defendant’s automobile. The Court held the Government
searched the automobile because it “physically occupied
private property [of the defendant] for the purpose of
obtaining information.” 565 U. S., at 404. So in Jones it
was “not necessary to inquire about the target’s expecta-
tion of privacy in his vehicle’s movements.” Grady v.
North Carolina, 575 U. S. ___, ___ (2015) (per curiam) (slip
op., at 3).
Despite that clear delineation of the Court’s holding in
Jones, the Court today declares that Jones applied the
“ ‘different constitutional principles’ ” alluded to in Knotts
to establish that an individual has an expectation of pri-
vacy in the sum of his whereabouts. Ante, at 8, 12. For that
proposition the majority relies on the two concurring
opinions in Jones, one of which stated that “longer term
GPS monitoring in investigations of most offenses impinges
on expectations of privacy.” 565 U. S., at 430 (ALITO, J.,
concurring). But Jones involved direct governmental
surveillance of a defendant’s automobile without judicial
16 CARPENTER v. UNITED STATES
KENNEDY, J., dissenting
authorization—specifically, GPS surveillance accurate
within 50 to 100 feet. Id., at 402403. Even assuming
that the different constitutional principles mentioned in
Knotts would apply in a case like Jones—a proposition the
Court was careful not to announce in Jones, supra, at
412413—those principles are inapplicable here. Cases
like this one, where the Government uses court-approved
compulsory process to obtain records owned and controlled
by a third party, are governed by the two majority opin-
ions in Miller and Smith.
B
The Court continues its analysis by misinterpreting
Miller and Smith, and then it reaches the wrong outcome
on these facts even under its flawed standard.
The Court appears, in my respectful view, to read Miller
and Smith to establish a balancing test. For each “quali-
tatively different category” of information, the Court
suggests, the privacy interests at stake must be weighed
against the fact that the information has been disclosed to
a third party. See ante, at 11, 1517. When the privacy
interests are weighty enough to “overcome” the third-party
disclosure, the Fourth Amendment’s protections apply.
See ante, at 17.
That is an untenable reading of Miller and Smith. As
already discussed, the fact that information was relin-
quished to a third party was the entire basis for conclud-
ing that the defendants in those cases lacked a reasonable
expectation of privacy. Miller and Smith do not establish
the kind of category-by-category balancing the Court today
prescribes.
But suppose the Court were correct to say that Miller
and Smith rest on so imprecise a foundation. Still the
Court errs, in my submission, when it concludes that cell-
site records implicate greater privacy interests—and thus
deserve greater Fourth Amendment protection—than
Cite as: 585 U. S. ____ (2018) 17
KENNEDY, J., dissenting
financial records and telephone records.
Indeed, the opposite is true. A person’s movements are
not particularly private. As the Court recognized in
Knotts, when the defendant there “traveled over the public
streets he voluntarily conveyed to anyone who wanted to
look the fact that he was traveling over particular roads in
a particular direction, the fact of whatever stops he made,
and the fact of his final destination.” 460 U. S., at
281282. Today expectations of privacy in one’s location
are, if anything, even less reasonable than when the Court
decided Knotts over 30 years ago. Millions of Americans
choose to share their location on a daily basis, whether by
using a variety of location-based services on their phones,
or by sharing their location with friends and the public at
large via social media.
And cell-site records, as already discussed, disclose a
person’s location only in a general area. The records at
issue here, for example, revealed Carpenter’s location
within an area covering between around a dozen and
several hundred city blocks. “Areas of this scale might
encompass bridal stores and Bass Pro Shops, gay bars and
straight ones, a Methodist church and the local mosque.”
819 F. 3d 880, 889 (CA6 2016). These records could not
reveal where Carpenter lives and works, much less his
“ ‘familial, political, professional, religious, and sexual
associations.’ ” Ante, at 12 (quoting Jones, supra, at 415
(SOTOMAYOR, J., concurring)).
By contrast, financial records and telephone records do
“ ‘revea[l] . . . personal affairs, opinions, habits and associ-
ations.’ ” Miller, 425 U. S., at 451 (Brennan, J., dissent-
ing); see Smith, 442 U. S., at 751 (Marshall, J., dissent-
ing). What persons purchase and to whom they talk might
disclose how much money they make; the political and
religious organizations to which they donate; whether they
have visited a psychiatrist, plastic surgeon, abortion clinic,
or AIDS treatment center; whether they go to gay bars or
18 CARPENTER v. UNITED STATES
KENNEDY, J., dissenting
straight ones; and who are their closest friends and family
members. The troves of intimate information the Gov-
ernment can and does obtain using financial records and
telephone records dwarfs what can be gathered from cell-
site records.
Still, the Court maintains, cell-site records are “unique”
because they are “comprehensive” in their reach; allow for
retrospective collection; are “easy, cheap, and efficient
compared to traditional investigative tools”; and are not
exposed to cell phone service providers in a meaningfully
voluntary manner. Ante, at 1113, 17, 22. But many
other kinds of business records can be so described. Fi-
nancial records are of vast scope. Banks and credit card
companies keep a comprehensive account of almost every
transaction an individual makes on a daily basis. “With
just the click of a button, the Government can access each
[company’s] deep repository of historical [financial] infor-
mation at practically no expense.” Ante, at 1213. And
the decision whether to transact with banks and credit
card companies is no more or less voluntary than the
decision whether to use a cell phone. Today, just as when
Miller was decided, “ ‘it is impossible to participate in the
economic life of contemporary society without maintaining
a bank account.’ ” 425 U. S., at 451 (Brennan, J., dissent-
ing). But this Court, nevertheless, has held that individ-
uals do not have a reasonable expectation of privacy in
financial records.
Perhaps recognizing the difficulty of drawing the consti-
tutional line between cell-site records and financial and
telephonic records, the Court posits that the accuracy of
cell-site records “is rapidly approaching GPS-level preci-
sion.” Ante, at 14. That is certainly plausible in the era of
cyber technology, yet the privacy interests associated with
location information, which is often disclosed to the public
at large, still would not outweigh the privacy interests
implicated by financial and telephonic records.
Cite as: 585 U. S. ____ (2018) 19
KENNEDY, J., dissenting
Perhaps more important, those future developments are
no basis upon which to resolve this case. In general, the
Court “risks error by elaborating too fully on the Fourth
Amendment implications of emerging technology before its
role in society has become clear.” Ontario v. Quon, 560
U. S. 746, 759 (2010). That judicial caution, prudent in
most cases, is imperative in this one.
Technological changes involving cell phones have com-
plex effects on crime and law enforcement. Cell phones
make crimes easier to coordinate and conceal, while also
providing the Government with new investigative tools
that may have the potential to upset traditional privacy
expectations. See Kerr, An Equilibrium-Adjustment
Theory of the Fourth Amendment, 125 Harv. L. Rev 476,
512517 (2011). How those competing effects balance
against each other, and how property norms and expecta-
tions of privacy form around new technology, often will be
difficult to determine during periods of rapid technological
change. In those instances, and where the governing legal
standard is one of reasonableness, it is wise to defer to
legislative judgments like the one embodied in §2703(d) of
the Stored Communications Act. See Jones, 565 U. S., at
430 (ALITO, J., concurring). In §2703(d) Congress weighed
the privacy interests at stake and imposed a judicial check
to prevent executive overreach. The Court should be wary
of upsetting that legislative balance and erecting constitu-
tional barriers that foreclose further legislative instruc-
tions. See Quon, supra, at 759. The last thing the Court
should do is incorporate an arbitrary and outside limit—in
this case six days’ worth of cell-site records—and use it as
the foundation for a new constitutional framework. The
Court’s decision runs roughshod over the mechanism
Congress put in place to govern the acquisition of cell-site
records and closes off further legislative debate on these
issues.
20 CARPENTER v. UNITED STATES
KENNEDY, J., dissenting
C
The Court says its decision is a “narrow one.” Ante, at
17. But its reinterpretation of Miller and Smith will have
dramatic consequences for law enforcement, courts, and
society as a whole.
Most immediately, the Court’s holding that the Gov-
ernment must get a warrant to obtain more than six days
of cell-site records limits the effectiveness of an important
investigative tool for solving serious crimes. As this case
demonstrates, cell-site records are uniquely suited to help
the Government develop probable cause to apprehend
some of the Nation’s most dangerous criminals: serial
killers, rapists, arsonists, robbers, and so forth. See also,
e.g., Davis, 785 F. 3d, at 500501 (armed robbers); Brief
for Alabama et al. as Amici Curiae 2122 (serial killer).
These records often are indispensable at the initial stages
of investigations when the Government lacks the evidence
necessary to obtain a warrant. See United States v. Pem-
brook, 876 F. 3d 812, 816819 (CA6 2017). And the long-
term nature of many serious crimes, including serial
crimes and terrorism offenses, can necessitate the use of
significantly more than six days of cell-site records. The
Court’s arbitrary 6-day cutoff has the perverse effect
of nullifying Congress’ reasonable framework for obtain-
ing cell-site records in some of the most serious criminal
investigations.
The Court’s decision also will have ramifications that
extend beyond cell-site records to other kinds of infor-
mation held by third parties, yet the Court fails “to pro-
vide clear guidance to law enforcement” and courts on key
issues raised by its reinterpretation of Miller and Smith.
Riley v. California, 573 U. S. ___, ___ (2014) (slip op.,
at 22).
First, the Court’s holding is premised on cell-site records
being a “distinct category of information” from other busi-
Cite as: 585 U. S. ____ (2018) 21
KENNEDY, J., dissenting
ness records. Ante, at 15. But the Court does not explain
what makes something a distinct category of information.
Whether credit card records are distinct from bank rec-
ords; whether payment records from digital wallet applica-
tions are distinct from either; whether the electronic bank
records available today are distinct from the paper and
microfilm records at issue in Miller; or whether cell-phone
call records are distinct from the home-phone call records
at issue in Smith, are just a few of the difficult questions
that require answers under the Court’s novel conception of
Miller and Smith.
Second, the majority opinion gives courts and law en-
forcement officers no indication how to determine whether
any particular category of information falls on the finan-
cial-records side or the cell-site-records side of its newly
conceived constitutional line. The Court’s multifactor
analysis—considering intimacy, comprehensiveness, ex-
pense, retrospectivity, and voluntariness—puts the law on
a new and unstable foundation.
Third, even if a distinct category of information is
deemed to be more like cell-site records than financial
records, courts and law enforcement officers will have to
guess how much of that information can be requested
before a warrant is required. The Court suggests that less
than seven days of location information may not require a
warrant. See ante, at 11, n. 3; see also ante, at 1718
(expressing no opinion on “real-time CSLI,” tower dumps,
and security-camera footage). But the Court does not
explain why that is so, and nothing in its opinion even
alludes to the considerations that should determine
whether greater or lesser thresholds should apply to in-
formation like IP addresses or website browsing history.
Fourth, by invalidating the Government’s use of court-
approved compulsory process in this case, the Court calls
into question the subpoena practices of federal and state
grand juries, legislatures, and other investigative bodies,
22 CARPENTER v. UNITED STATES
KENNEDY, J., dissenting
as JUSTICE ALITO’s opinion explains. See post, at 219
(dissenting opinion). Yet the Court fails even to mention
the serious consequences this will have for the proper
administration of justice.
In short, the Court’s new and uncharted course will
inhibit law enforcement and “keep defendants and judges
guessing for years to come.” Riley, 573 U. S., at ___ (slip
op., at 25) (internal quotation marks omitted).
* * *
This case should be resolved by interpreting accepted
property principles as the baseline for reasonable expecta-
tions of privacy. Here the Government did not search
anything over which Carpenter could assert ownership or
control. Instead, it issued a court-authorized subpoena to
a third party to disclose information it alone owned and
controlled. That should suffice to resolve this case.
Having concluded, however, that the Government
searched Carpenter when it obtained cell-site records from
his cell phone service providers, the proper resolution of
this case should have been to remand for the Court of
Appeals to determine in the first instance whether the
search was reasonable. Most courts of appeals, believing
themselves bound by Miller and Smith, have not grappled
with this question. And the Court’s reflexive imposition of
the warrant requirement obscures important and difficult
issues, such as the scope of Congress’ power to authorize
the Government to collect new forms of information using
processes that deviate from traditional warrant proce-
dures, and how the Fourth Amendment’s reasonableness
requirement should apply when the Government uses
compulsory process instead of engaging in an actual,
physical search.
These reasons all lead to this respectful dissent.
Cite as: 585 U. S. ____ (2018) 23
KENNEDY
Appendix , J., dissenting
to opinion of KENNEDY, J.
APPENDIX
Ҥ2703. Required disclosure of customer communi-
cations or records
“(d) REQUIREMENTS FOR COURT ORDER.—A court order
for disclosure under subsection (b) or (c) may be issued by
any court that is a court of competent jurisdiction and
shall issue only if the governmental entity offers specific
and articulable facts showing that there are reasonable
grounds to believe that the contents of a wire or electronic
communication, or the records or other information
sought, are relevant and material to an ongoing criminal
investigation. In the case of a State governmental author-
ity, such a court order shall not issue if prohibited by the
law of such State. A court issuing an order pursuant to
this section, on a motion made promptly by the service
provider, may quash or modify such order, if the infor-
mation or records requested are unusually voluminous in
nature or compliance with such order otherwise would
cause an undue burden on such provider.”
Cite as: 585 U. S. ____ (2018) 1
THOMAS, J., dissenting
SUPREME COURT OF THE UNITED STATES
_________________
No. 16–402
_________________
TIMOTHY IVORY CARPENTER, PETITIONER v.
UNITED STATES
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE SIXTH CIRCUIT
[June 22, 2018]
JUSTICE THOMAS, dissenting.
This case should not turn on “whether” a search oc
curred. Ante, at 1. It should turn, instead, on whose
property was searched. The Fourth Amendment guaran
tees individuals the right to be secure from unreasonable
searches of “their persons, houses, papers, and effects.”
(Emphasis added.) In other words, “each person has the
right to be secure against unreasonable searches . . . in his
own person, house, papers, and effects.” Minnesota v.
Carter, 525 U. S. 83, 92 (1998) (Scalia, J., concurring). By
obtaining the cell-site records of MetroPCS and Sprint, the
Government did not search Carpenter’s property. He did
not create the records, he does not maintain them, he
cannot control them, and he cannot destroy them. Neither
the terms of his contracts nor any provision of law makes
the records his. The records belong to MetroPCS and
Sprint.
The Court concludes that, although the records are not
Carpenter’s, the Government must get a warrant because
Carpenter had a reasonable “expectation of privacy” in the
location information that they reveal. Ante, at 11. I agree
with JUSTICE KENNEDY, JUSTICE ALITO, JUSTICE
GORSUCH, and every Court of Appeals to consider the
question that this is not the best reading of our
precedents.
2 CARPENTER v. UNITED STATES
THOMAS, J., dissenting
The more fundamental problem with the Court’s opin
ion, however, is its use of the “reasonable expectation of
privacy” test, which was first articulated by Justice Har
lan in Katz v. United States, 389 U. S. 347, 360–361 (1967)
(concurring opinion). The Katz test has no basis in the
text or history of the Fourth Amendment. And, it invites
courts to make judgments about policy, not law. Until we
confront the problems with this test, Katz will continue to
distort Fourth Amendment jurisprudence. I respectfully
dissent.
I
Katz was the culmination of a series of decisions apply
ing the Fourth Amendment to electronic eavesdropping.
The first such decision was Olmstead v. United States, 277
U. S. 438 (1928), where federal officers had intercepted the
defendants’ conversations by tapping telephone lines near
their homes. Id., at 456–457. In an opinion by Chief
Justice Taft, the Court concluded that this wiretap did not
violate the Fourth Amendment. No “search” occurred,
according to the Court, because the officers did not physi
cally enter the defendants’ homes. Id., at 464–466. And
neither the telephone lines nor the defendants’ intangible
conversations qualified as “persons, houses, papers, [or]
effects” within the meaning of the Fourth Amendment.
Ibid.1 In the ensuing decades, this Court adhered to
——————
1 Justice Brandeis authored the principal dissent in Olmstead. He
consulted the “underlying purpose,” rather than “the words of the
[Fourth] Amendment,” to conclude that the wiretap was a search. 277
U. S., at 476. In Justice Brandeis’ view, the Framers “recognized the
significance of man’s spiritual nature, of his feelings and of his intel
lect” and “sought to protect Americans in their beliefs, their thoughts,
their emotions and their sensations.” Id., at 478. Thus, “every unjusti
fiable intrusion by the Government upon the privacy of the individual,
whatever the means employed,” should constitute an unreasonable
search under the Fourth Amendment. Ibid.
Cite as: 585 U. S. ____ (2018) 3
THOMAS, J., dissenting
Olmstead and rejected Fourth Amendment challenges to
various methods of electronic surveillance. See On Lee v.
United States, 343 U. S. 747, 749–753 (1952) (use of mi
crophone to overhear conversations with confidential
informant); Goldman v. United States, 316 U. S. 129, 131–
132, 135–136 (1942) (use of detectaphone to hear conver
sations in office next door).
In the 1960’s, however, the Court began to retreat from
Olmstead. In Silverman v. United States, 365 U. S. 505
(1961), for example, federal officers had eavesdropped on
the defendants by driving a “spike mike” several inches
into the house they were occupying. Id., at 506–507. This
was a “search,” the Court held, because the “unauthorized
physical penetration into the premises” was an “actual
intrusion into a constitutionally protected area.” Id., at
509, 512. The Court did not mention Olmstead’s other
holding that intangible conversations are not “persons,
houses, papers, [or] effects.” That omission was signifi
cant. The Court confirmed two years later that “[i]t fol
lows from [Silverman] that the Fourth Amendment may
protect against the overhearing of verbal statements as
well as against the more traditional seizure of ‘papers and
effects.’ ” Wong Sun v. United States, 371 U. S. 471, 485
(1963); accord, Berger v. New York, 388 U. S. 41, 51 (1967).
In Katz, the Court rejected Olmstead’s remaining hold-
ing—that eavesdropping is not a search absent a physical
intrusion into a constitutionally protected area. The
federal officers in Katz had intercepted the defendant’s
conversations by attaching an electronic device to the
outside of a public telephone booth. 389 U. S., at 348. The
Court concluded that this was a “search” because the
officers “violated the privacy upon which [the defendant]
justifiably relied while using the telephone booth.” Id., at
353. Although the device did not physically penetrate the
booth, the Court overruled Olmstead and held that “the
reach of [the Fourth] Amendment cannot turn upon the
4 CARPENTER v. UNITED STATES
THOMAS, J., dissenting
presence or absence of a physical intrusion.” 389 U. S., at
353. The Court did not explain what should replace
Olmstead’s physical-intrusion requirement. It simply
asserted that “the Fourth Amendment protects people, not
places” and “what [a person] seeks to preserve as private
. . . may be constitutionally protected.” 389 U. S., at 351.
Justice Harlan’s concurrence in Katz attempted to artic
ulate the standard that was missing from the majority
opinion. While Justice Harlan agreed that “ ‘the Fourth
Amendment protects people, not places,’ ” he stressed that
“[t]he question . . . is what protection it affords to those
people,” and “the answer . . . requires reference to a
‘place.’ ” Id., at 361. Justice Harlan identified a “twofold
requirement” to determine when the protections of the
Fourth Amendment apply: “first that a person have exhib
ited an actual (subjective) expectation of privacy and,
second, that the expectation be one that society is pre
pared to recognize as ‘reasonable.’ ” Ibid.
Justice Harlan did not cite anything for this “expecta
tion of privacy” test, and the parties did not discuss it in
their briefs. The test appears to have been presented for
the first time at oral argument by one of the defendant’s
lawyers. See Winn, Katz and the Origins of the “Reason-
able Expectation of Privacy” Test, 40 McGeorge L. Rev. 1,
9–10 (2009). The lawyer, a recent law-school graduate,
apparently had an “[e]piphany” while preparing for oral
argument. Schneider, Katz v. United States: The Untold
Story, 40 McGeorge L. Rev. 13, 18 (2009). He conjectured
that, like the “reasonable person” test from his Torts class,
the Fourth Amendment should turn on “whether a rea
sonable person . . . could have expected his communication
to be private.” Id., at 19. The lawyer presented his new
theory to the Court at oral argument. See, e.g., Tr. of Oral
Arg. in Katz v. United States, O. T. 1967, No. 35, p. 5
(proposing a test of “whether or not, objectively speaking,
the communication was intended to be private”); id., at 11
Cite as: 585 U. S. ____ (2018) 5
THOMAS, J., dissenting
(“We propose a test using a way that’s not too dissimilar
from the tort ‘reasonable man’ test”). After some question
ing from the Justices, the lawyer conceded that his test
should also require individuals to subjectively expect
privacy. See id., at 12. With that modification, Justice
Harlan seemed to accept the lawyer’s test almost verbatim
in his concurrence.
Although the majority opinion in Katz had little practi
cal significance after Congress enacted the Omnibus
Crime Control and Safe Streets Act of 1968, Justice Har
lan’s concurrence profoundly changed our Fourth Amend
ment jurisprudence. It took only one year for the full
Court to adopt his two-pronged test. See Terry v. Ohio,
392 U. S. 1, 10 (1968). And by 1979, the Court was de
scribing Justice Harlan’s test as the “lodestar” for deter
mining whether a “search” had occurred. Smith v. Mary-
land, 442 U. S. 735, 739 (1979). Over time, the Court
minimized the subjective prong of Justice Harlan’s test.
See Kerr, Katz Has Only One Step: The Irrelevance of
Subjective Expectations, 82 U. Chi. L. Rev. 113 (2015).
That left the objective prong—the “reasonable expectation
of privacy” test that the Court still applies today. See
ante, at 5; United States v. Jones, 565 U. S. 400, 406
(2012).
II
Under the Katz test, a “search” occurs whenever “gov
ernment officers violate a person’s ‘reasonable expectation
of privacy.’ ” Jones, supra, at 406. The most glaring prob
lem with this test is that it has “no plausible foundation in
the text of the Fourth Amendment.” Carter, 525 U. S., at
97 (opinion of Scalia, J.). The Fourth Amendment, as
relevant here, protects “[t]he right of the people to be
secure in their persons, houses, papers, and effects,
against unreasonable searches.” By defining “search” to
mean “any violation of a reasonable expectation of pri-
6 CARPENTER v. UNITED STATES
THOMAS, J., dissenting
vacy,” the Katz test misconstrues virtually every one of
these words.
A
The Katz test distorts the original meaning of
“searc[h]”—the word in the Fourth Amendment that it
purports to define, see ante, at 5; Smith, supra. Under the
Katz test, the government conducts a search anytime it
violates someone’s “reasonable expectation of privacy.”
That is not a normal definition of the word “search.”
At the founding, “search” did not mean a violation of
someone’s reasonable expectation of privacy. The word
was probably not a term of art, as it does not appear in
legal dictionaries from the era. And its ordinary meaning
was the same as it is today: “ ‘[t]o look over or through for
the purpose of finding something; to explore; to examine
by inspection; as, to search the house for a book; to search
the wood for a thief.’ ” Kyllo v. United States, 533 U. S. 27,
32, n. 1 (2001) (quoting N. Webster, An American Diction
ary of the English Language 66 (1828) (reprint 6th ed.
1989)); accord, 2 S. Johnson, A Dictionary of the English
Language (5th ed. 1773) (“Inquiry by looking into every
suspected place”); N. Bailey, An Universal Etymological
English Dictionary (22d ed. 1770) (“a seeking after, a
looking for, &c.”); 2 J. Ash, The New and Complete Dic
tionary of the English Language (2d ed. 1795) (“An en
quiry, an examination, the act of seeking, an enquiry by
looking into every suspected place; a quest; a pursuit”); T.
Sheridan, A Complete Dictionary of the English Language
(6th ed. 1796) (similar). The word “search” was not asso
ciated with “reasonable expectation of privacy” until Jus
tice Harlan coined that phrase in 1967. The phrase “ex
pectation(s) of privacy” does not appear in the pre-Katz
federal or state case reporters, the papers of prominent
Cite as: 585 U. S. ____ (2018) 7
THOMAS, J., dissenting
Founders,2 early congressional documents and debates,3
collections of early American English texts,4 or early
American newspapers.5
B
The Katz test strays even further from the text by focus
ing on the concept of “privacy.” The word “privacy” does
not appear in the Fourth Amendment (or anywhere else in
the Constitution for that matter). Instead, the Fourth
Amendment references “[t]he right of the people to be
secure.” It then qualifies that right by limiting it to “per
sons” and three specific types of property: “houses, papers,
and effects.” By connecting the right to be secure to these
four specific objects, “[t]he text of the Fourth Amendment
reflects its close connection to property.” Jones, supra, at
405. “[P]rivacy,” by contrast, “was not part of the political
vocabulary of the [founding]. Instead, liberty and privacy
rights were understood largely in terms of property
rights.” Cloud, Property Is Privacy: Locke and Brandeis in
the Twenty-First Century, 55 Am. Crim. L. Rev. 37, 42
(2018).
Those who ratified the Fourth Amendment were quite
familiar with the notion of security in property. Security
in property was a prominent concept in English law. See,
e.g., 3 W. Blackstone, Commentaries on the Laws of Eng-
——————
2 National Archives, Library of Congress, Founders Online, https://
founders.archives.gov (all Internet materials as last visited June
18, 2018).
3 A Century of Lawmaking For A New Nation, U. S. Congressional
Documents and Debates, 1774–1875 (May 1, 2003), https://memory.loc
.gov/ammem/amlaw/lawhome.html.
4 Corpus of Historical American English, https://corpus.byu.edu/coha;
Google Books (American), https://googlebooks.byu.edu/x.asp; Corpus of
Founding Era American English, https://lawncl.byu.edu/cofea.
5 Readex, America’s Historical Newspapers (2018), https://
www.readex.com/content/americas-historical-newspapers.
8 CARPENTER v. UNITED STATES
THOMAS, J., dissenting
land 288 (1768) (“[E]very man’s house is looked upon by
the law to be his castle”); 3 E. Coke, Institutes of Laws of
England 162 (6th ed. 1680) (“[F]or a man[’]s house is his
Castle, & domus sua cuique est tutissimum refugium
[each man’s home is his safest refuge]”). The political
philosophy of John Locke, moreover, “permeated the 18th
century political scene in America.” Obergefell v. Hodges,
576 U. S. ___, ___ (2015) (THOMAS, J., dissenting) (slip op.,
at 8). For Locke, every individual had a property right “in
his own person” and in anything he “removed from the
common state [of] Nature” and “mixed his labour with.”
Second Treatise of Civil Government §27 (1690). Because
property is “very unsecure” in the state of nature, §123,
individuals form governments to obtain “a secure enjoy
ment of their properties.” §95. Once a government is
formed, however, it cannot be given “a power to destroy
that which every one designs to secure”; it cannot legiti
mately “endeavour to take away, and destroy the property
of the people,” or exercise “an absolute power over [their]
lives, liberties, and estates.” §222.
The concept of security in property recognized by Locke
and the English legal tradition appeared throughout the
materials that inspired the Fourth Amendment. In Entick
v. Carrington, 19 How. St. Tr. 1029 (C. P. 1765)—a her
alded decision that the founding generation considered
“the true and ultimate expression of constitutional law,”
Boyd v. United States, 116 U. S. 616, 626 (1886)—Lord
Camden explained that “[t]he great end, for which men
entered into society, was to secure their property.” 19
How. St. Tr., at 1066. The American colonists echoed this
reasoning in their “widespread hostility” to the Crown’s
writs of assistance6—a practice that inspired the Revolu
——————
6 Writs of assistance were “general warrants” that gave “customs
officials blanket authority to search where they pleased for goods
Cite as: 585 U. S. ____ (2018) 9
THOMAS, J., dissenting
tion and became “[t]he driving force behind the adoption of
the [Fourth] Amendment.” United States v. Verdugo-
Urquidez, 494 U. S. 259, 266 (1990). Prominent colonists
decried the writs as destroying “ ‘domestic security’ ” by
permitting broad searches of homes. M. Smith, The Writs
of Assistance Case 475 (1978) (quoting a 1772 Boston town
meeting); see also id., at 562 (complaining that “ ‘every
householder in this province, will necessarily become less
secure than he was before this writ’ ” (quoting a 1762
article in the Boston Gazette)); id., at 493 (complaining
that the writs were “ ‘expressly contrary to the common
law, which ever regarded a man’s house as his castle, or a
place of perfect security’ ” (quoting a 1768 letter from John
Dickinson)). John Otis, who argued the famous Writs of
Assistance case, contended that the writs violated “ ‘the
fundamental Principl[e] of Law’ ” that “ ‘[a] Man who is
quiet, is as secure in his House, as a Prince in his Castle.’ ”
Id., at 339 (quoting John Adam’s notes). John Adams
attended Otis’ argument and later drafted Article XIV of
the Massachusetts Constitution,7 which served as a model
for the Fourth Amendment. See Clancy, The Framers’
Intent: John Adams, His Era, and the Fourth Amendment,
86 Ind. L. J. 979, 982 (2011); Donahue, The Original
Fourth Amendment, 83 U. Chi. L. Rev. 1181, 1269 (2016)
——————
imported in violation of the British tax laws.” Stanford v. Texas, 379
U. S. 476, 481 (1965).
7 “Every subject has a right to be secure from all unreasonable
searches and seizures of his person, his house, his papers, and all his
possessions. All warrants, therefore, are contrary to right, if the cause
or foundation of them be not previously supported by oath or affirma
tion, and if the order in the warrant to a civil officer, to make search in
suspected places, or to arrest one or more suspected persons, or to seize
their property, be not accompanied with a special designation of the
person or objects of search, arrest, or seizure; and no warrant ought to
be issued but in cases, and with the formalities prescribed by the laws.”
Mass. Const., pt. I, Art. XIV (1780).
10 CARPENTER v. UNITED STATES
THOMAS, J., dissenting
(Donahue). Adams agreed that “[p]roperty must be se
cured, or liberty cannot exist.” Discourse on Davila, in 6
The Works of John Adams 280 (C. Adams ed. 1851).
Of course, the founding generation understood that, by
securing their property, the Fourth Amendment would
often protect their privacy as well. See, e.g., Boyd, supra,
at 630 (explaining that searches of houses invade “the
privacies of life”); Wilkes v. Wood, 19 How. St. Tr. 1153,
1154 (C. P. 1763) (argument of counsel contending that
seizures of papers implicate “our most private concerns”).
But the Fourth Amendment’s attendant protection of
privacy does not justify Katz’s elevation of privacy as the
sine qua non of the Amendment. See T. Clancy, The
Fourth Amendment: Its History and Interpretation §3.4.4,
p. 78 (2008) (“[The Katz test] confuse[s] the reasons for
exercising the protected right with the right itself. A
purpose of exercising one’s Fourth Amendment rights
might be the desire for privacy, but the individual’s motiva
tion is not the right protected”); cf. United States v. Gonzalez-
Lopez, 548 U. S. 140, 145 (2006) (rejecting “a line of
reasoning that ‘abstracts from the right to its purposes,
and then eliminates the right’ ”). As the majority opinion
in Katz recognized, the Fourth Amendment “cannot be
translated into a general constitutional ‘right to privacy,’ ”
as its protections “often have nothing to do with privacy at
all.” 389 U. S., at 350. Justice Harlan’s focus on privacy
in his concurrence—an opinion that was issued between
Griswold v. Connecticut, 381 U. S. 479 (1965), and Roe v.
Wade, 410 U. S. 113 (1973)—reflects privacy’s status as
the organizing constitutional idea of the 1960’s and 1970’s.
The organizing constitutional idea of the founding era, by
contrast, was property.
C
In shifting the focus of the Fourth Amendment from
property to privacy, the Katz test also reads the words
Cite as: 585 U. S. ____ (2018) 11
THOMAS, J., dissenting
“persons, houses, papers, and effects” out of the text. At
its broadest formulation, the Katz test would find a search
“wherever an individual may harbor a reasonable ‘expecta
tion of privacy.’ ” Terry, 392 U. S., at 9 (emphasis added).
The Court today, for example, does not ask whether cell-
site location records are “persons, houses, papers, [or]
effects” within the meaning of the Fourth Amendment.8
Yet “persons, houses, papers, and effects” cannot mean
“anywhere” or “anything.” Katz’s catchphrase that “the
Fourth Amendment protects people, not places,” is not a
serious attempt to reconcile the constitutional text. See
Carter, 525 U. S., at 98, n. 3 (opinion of Scalia, J.). The
Fourth Amendment obviously protects people; “[t]he ques
tion . . . is what protection it affords to those people.”
Katz, 389 U. S., at 361 (Harlan, J., concurring). The
Founders decided to protect the people from unreasonable
searches and seizures of four specific things—persons,
houses, papers, and effects. They identified those four
categories as “the objects of privacy protection to which
the Constitution would extend, leaving further expansion
to the good judgment . . . of the people through their rep
resentatives in the legislature.” Carter, supra, at 97–98
(opinion of Scalia, J.).
This limiting language was important to the founders.
Madison’s first draft of the Fourth Amendment used a
different phrase: “their persons, their houses, their papers,
and their other property.” 1 Annals of Cong. 452 (1789)
——————
8 The answer to that question is not obvious. Cell-site location rec
ords are business records that mechanically collect the interactions
between a person’s cell phone and the company’s towers; they are not
private papers and do not reveal the contents of any communications.
Cf. Schnapper, Unreasonable Searches and Seizures of Papers, 71 Va.
L. Rev. 869, 923–924 (1985) (explaining that business records that do
not reveal “personal or speech-related confidences” might not satisfy
the original meaning of “papers”).
12 CARPENTER v. UNITED STATES
THOMAS, J., dissenting
(emphasis added). In one of the few changes made to
Madison’s draft, the House Committee of Eleven changed
“other property” to “effects.” See House Committee of
Eleven Report (July 28, 1789), in N. Cogan, The Complete
Bill of Rights 334 (2d ed. 2015). This change might have
narrowed the Fourth Amendment by clarifying that it does
not protect real property (other than houses). See Oliver
v. United States, 466 U. S. 170, 177, and n. 7 (1984); Da
vies, Recovering the Original Fourth Amendment, 98
Mich. L. Rev. 547, 709–714 (1999) (Davies). Or the change
might have broadened the Fourth Amendment by clarify
ing that it protects commercial goods, not just personal
possessions. See Donahue 1301. Or it might have done
both. Whatever its ultimate effect, the change reveals
that the Founders understood the phrase “persons, houses,
papers, and effects” to be an important measure of the
Fourth Amendment’s overall scope. See Davies 710. The
Katz test, however, displaces and renders that phrase
entirely “superfluous.” Jones, 565 U. S., at 405.
D
“[P]ersons, houses, papers, and effects” are not the only
words that the Katz test reads out of the Fourth Amend
ment. The Fourth Amendment specifies that the people
have a right to be secure from unreasonable searches of
“their” persons, houses, papers, and effects. Although
phrased in the plural, “[t]he obvious meaning of [‘their’] is
that each person has the right to be secure against unrea
sonable searches and seizures in his own person, house,
papers, and effects.” Carter, supra, at 92 (opinion of Sca-
lia, J.); see also District of Columbia v. Heller, 554 U. S.
570, 579 (2008) (explaining that the Constitution uses the
plural phrase “the people” to “refer to individual rights,
not ‘collective’ rights”). Stated differently, the word “their”
means, at the very least, that individuals do not have
Fourth Amendment rights in someone else’s property. See
Cite as: 585 U. S. ____ (2018) 13
THOMAS, J., dissenting
Carter, supra, at 92–94 (opinion of Scalia, J.). Yet, under
the Katz test, individuals can have a reasonable expecta
tion of privacy in another person’s property. See, e.g.,
Carter, 525 U. S., at 89 (majority opinion) (“[A] person
may have a legitimate expectation of privacy in the house
of someone else”). Until today, our precedents have not
acknowledged that individuals can claim a reasonable
expectation of privacy in someone else’s business records.
See ante, at 2 (KENNEDY, J., dissenting). But the Court
erases that line in this case, at least for cell-site location
records. In doing so, it confirms that the Katz test does
not necessarily require an individual to prove that the
government searched his person, house, paper, or effect.
Carpenter attempts to argue that the cell-site records
are, in fact, his “papers,” see Brief for Petitioner 32–35;
Reply Brief 14–15, but his arguments are unpersuasive,
see ante, at 12–13 (opinion of KENNEDY, J.); post, at 20–23
(ALITO, J., dissenting). Carpenter stipulated below that
the cell-site records are the business records of Sprint and
MetroPCS. See App. 51. He cites no property law in his
briefs to this Court, and he does not explain how he has a
property right in the companies’ records under the law of
any jurisdiction at any point in American history. If
someone stole these records from Sprint or MetroPCS,
Carpenter does not argue that he could recover in a tradi
tional tort action. Nor do his contracts with Sprint and
MetroPCS make the records his, even though such provi
sions could exist in the marketplace. Cf., e.g., Google
Terms of Service, https://policies.google.com/terms (“Some
of our Services allow you to upload, submit, store, send or
receive content. You retain ownership of any intellectual
property rights that you hold in that content. In short,
what belongs to you stays yours”).
Instead of property, tort, or contract law, Carpenter
relies on the federal Telecommunications Act of 1996 to
demonstrate that the cell site records are his papers. The
14 CARPENTER v. UNITED STATES
THOMAS, J., dissenting
Telecommunications Act generally bars cell-phone compa
nies from disclosing customers’ cell site location infor
mation to the public. See 47 U. S. C. §222(c). This is
sufficient to make the records his, Carpenter argues,
because the Fourth Amendment merely requires him to
identify a source of “positive law” that “protects against
access by the public without consent.” Brief for Petitioner
32–33 (citing Baude & Stern, The Positive Law Model of
the Fourth Amendment, 129 Harv. L. Rev. 1821, 1825–
1826 (2016); emphasis deleted).
Carpenter is mistaken. To come within the text of the
Fourth Amendment, Carpenter must prove that the cell-
site records are his; positive law is potentially relevant
only insofar as it answers that question. The text of the
Fourth Amendment cannot plausibly be read to mean “any
violation of positive law” any more than it can plausibly be
read to mean “any violation of a reasonable expectation of
privacy.”
Thus, the Telecommunications Act is insufficient be
cause it does not give Carpenter a property right in the
cell-site records. Section 222, titled “Privacy of customer
information,” protects customers’ privacy by preventing
cell-phone companies from disclosing sensitive information
about them. The statute creates a “duty to protect the
confidentiality” of information relating to customers,
§222(a), and creates “[p]rivacy requirements” that limit
the disclosure of that information, §222(c)(1). Nothing in
the text pre-empts state property law or gives customers a
property interest in the companies’ business records (as
suming Congress even has that authority).9 Although
——————
9 Carpenter relies on an order from the Federal Communications
Commission (FCC), which weakly states that “ ‘[t]o the extent [a cus
tomer’s location information] is property, . . . it is better understood as
belonging to the customer, not the carrier.’ ” Brief for Petitioner 34, and
n. 23 (quoting 13 FCC Rcd. 8061, 8093 ¶43 (1998); emphasis added).
Cite as: 585 U. S. ____ (2018) 15
THOMAS, J., dissenting
§222 “protects the interests of individuals against wrong
ful uses or disclosures of personal data, the rationale for
these legal protections has not historically been grounded
on a perception that people have property rights in per
sonal data as such.” Samuelson, Privacy as Intellectual
Property? 52 Stan. L. Rev. 1125, 1130–1131 (2000) (foot
note omitted). Any property rights remain with the
companies.
E
The Katz test comes closer to the text of the Fourth
Amendment when it asks whether an expectation of pri-
vacy is “reasonable,” but it ultimately distorts that term as
well. The Fourth Amendment forbids “unreasonable
searches.” In other words, reasonableness determines the
legality of a search, not “whether a search . . . within the
meaning of the Constitution has occurred.” Carter, 525
U. S., at 97 (opinion of Scalia, J.) (internal quotation
marks omitted).
Moreover, the Katz test invokes the concept of reason-
ableness in a way that would be foreign to the ratifiers of
the Fourth Amendment. Originally, the word “unreason-
able” in the Fourth Amendment likely meant “against
reason”—as in “against the reason of the common law.”
See Donahue 1270–1275; Davies 686–693; California v.
Acevedo, 500 U. S. 565, 583 (1991) (Scalia, J., concurring
in judgment). At the founding, searches and seizures were
——————
But this order was vacated by the Court of Appeals for the Tenth
Circuit. U. S. West, Inc. v. FCC, 182 F. 3d 1224, 1240 (1999). Notably,
the carrier in that case argued that the FCC’s regulation of customer
information was a taking of its property. See id., at 1230. Although
the panel majority had no occasion to address this argument, see id., at
1239, n. 14, the dissent concluded that the carrier had failed to prove
the information was “property” at all, see id., at 1247–1248 (opinion of
Briscoe, J.).
16 CARPENTER v. UNITED STATES
THOMAS, J., dissenting
regulated by a robust body of common-law rules. See
generally W. Cuddihy, The Fourth Amendment: Origins
and Original Meaning 602–1791 (2009); e.g., Wilson v.
Arkansas, 514 U. S. 927, 931–936 (1995) (discussing the
common-law knock-and-announce rule). The search-and
seizure practices that the Founders feared most—such as
general warrants—were already illegal under the common
law, and jurists such as Lord Coke described violations of
the common law as “against reason.” See Donahue 1270–
1271, and n. 513. Locke, Blackstone, Adams, and other
influential figures shortened the phrase “against reason”
to “unreasonable.” See id., at 1270–1275. Thus, by pro
hibiting “unreasonable” searches and seizures in the
Fourth Amendment, the Founders ensured that the newly
created Congress could not use legislation to abolish the
established common-law rules of search and seizure. See
T. Cooley, Constitutional Limitations *303 (2d ed. 1871); 3
J. Story, Commentaries on the Constitution of the United
States §1895, p. 748 (1833).
Although the Court today maintains that its decision is
based on “Founding-era understandings,” ante, at 6, the
Founders would be puzzled by the Court’s conclusion as
well as its reasoning. The Court holds that the Govern
ment unreasonably searched Carpenter by subpoenaing
the cell-site records of Sprint and MetroPCS without a
warrant. But the Founders would not recognize the
Court’s “warrant requirement.” Ante, at 21. The common
law required warrants for some types of searches and
seizures, but not for many others. The relevant rule de
pended on context. See Acevedo, supra, at 583–584 (opin
ion of Scalia, J.); Amar, Fourth Amendment First Princi
ples, 107 Harv. L. Rev. 757, 763–770 (1994); Davies 738–
739. In cases like this one, a subpoena for third-party
documents was not a “search” to begin with, and the com
mon law did not limit the government’s authority to sub
poena third parties. See post, at 2–12 (ALITO, J., dissent
Cite as: 585 U. S. ____ (2018) 17
THOMAS, J., dissenting
ing). Suffice it to say, the Founders would be confused by
this Court’s transformation of their common-law protec
tion of property into a “warrant requirement” and a vague
inquiry into “reasonable expectations of privacy.”
III
That the Katz test departs so far from the text of the
Fourth Amendment is reason enough to reject it. But the
Katz test also has proved unworkable in practice. Jurists
and commentators tasked with deciphering our jurispru
dence have described the Katz regime as “an unpredictable
jumble,” “a mass of contradictions and obscurities,” “all
over the map,” “riddled with inconsistency and incoher
ence,” “a series of inconsistent and bizarre results that
[the Court] has left entirely undefended,” “unstable,”
“chameleon-like,” “ ‘notoriously unhelpful,’ ” “a conclusion
rather than a starting point for analysis,” “distressingly
unmanageable,” “a dismal failure,” “flawed to the core,”
“unadorned fiat,” and “inspired by the kind of logic that
produced Rube Goldberg’s bizarre contraptions.”10 Even
——————
10 Kugler & Strahilevitz, Actual Expectations of Privacy, Fourth
Amendment Doctrine, and the Mosaic Theory, 2015 S. Ct. Rev. 205,
261; Bradley, Two Models of the Fourth Amendment, 83 Mich. L. Rev.
1468 (1985); Kerr, Four Models of Fourth Amendment Protection, 60
Stan. L. Rev. 503, 505 (2007); Solove, Fourth Amendment Pragmatism,
51 Boston College L. Rev. 1511 (2010); Wasserstom & Seidman, The
Fourth Amendment as Constitutional Theory, 77 Geo. L. J. 19, 29
(1988); Colb, What Is a Search? Two Conceptual Flaws in Fourth
Amendment Doctrine and Some Hints of a Remedy, 55 Stan. L. Rev.
119, 122 (2002); Clancy, The Fourth Amendment: Its History and
Interpretation §3.3.4, p. 65 (2008); Minnesota v. Carter, 525 U. S. 83, 97
(1998) (Scalia, J., dissenting); State v. Campbell, 306 Ore. 157, 164, 759
P. 2d 1040, 1044 (1988); Wilkins, Defining the “Reasonable Expectation
of Privacy”: an Emerging Tripartite Analysis, 40 Vand. L. Rev. 1077,
1107 (1987); Yeager, Search, Seizure and the Positive Law: Expecta
tions of Privacy Outside the Fourth Amendment, 84 J. Crim. L. & C.
249, 251 (1993); Thomas, Time Travel, Hovercrafts, and the Framers:
18 CARPENTER v. UNITED STATES
THOMAS, J., dissenting
Justice Harlan, four years after penning his concurrence
in Katz, confessed that the test encouraged “the substitu
tion of words for analysis.” United States v. White, 401
U. S. 745, 786 (1971) (dissenting opinion).
After 50 years, it is still unclear what question the Katz
test is even asking. This Court has steadfastly declined to
elaborate the relevant considerations or identify any
meaningful constraints. See, e.g., ante, at 5 (“[N]o single
rubric definitively resolves which expectations of privacy
are entitled to protection”); O’Connor v. Ortega, 480 U. S.
709, 715 (1987) (plurality opinion) (“We have no talisman
that determines in all cases those privacy expectations
that society is prepared to accept as reasonable”); Oliver,
466 U. S., at 177 (“No single factor determines whether an
individual legitimately may claim under the Fourth
Amendment that a place should be free of government
intrusion”).
Justice Harlan’s original formulation of the Katz test
appears to ask a descriptive question: Whether a given
expectation of privacy is “one that society is prepared to
recognize as ‘reasonable.’ ” 389 U. S., at 361. As written,
the Katz test turns on society’s actual, current views about
the reasonableness of various expectations of privacy.
But this descriptive understanding presents several
problems. For starters, it is easily circumvented. If, for
example, “the Government were suddenly to announce on
nationwide television that all homes henceforth would be
subject to warrantless entry,” individuals could not realis
tically expect privacy in their homes. Smith, 442 U. S., at
740, n. 5; see also Chemerinsky, Rediscovering Brandeis’s
——————
James Madison Sees the Future and Rewrites the Fourth Amendment,
80 Notre Dame L. Rev. 1451, 1500 (2005); Rakas v. Illinois, 439 U. S.
128, 165 (1978) (White, J., dissenting); Cloud, Rube Goldberg Meets the
Constitution: The Supreme Court, Technology, and the Fourth
Amendment, 72 Miss. L. J. 5, 7 (2002).
Cite as: 585 U. S. ____ (2018) 19
THOMAS, J., dissenting
Right to Privacy, 45 Brandeis L. J. 643, 650 (2007) (“[Un
der Katz, t]he government seemingly can deny privacy just
by letting people know in advance not to expect any”). A
purely descriptive understanding of the Katz test also
risks “circular[ity].” Kyllo, 533 U. S., at 34. While this
Court is supposed to base its decisions on society’s expec
tations of privacy, society’s expectations of privacy are, in
turn, shaped by this Court’s decisions. See Posner, The
Uncertain Protection of Privacy by the Supreme Court,
1979 S. Ct. Rev. 173, 188 (“[W]hether [a person] will or
will not have [a reasonable] expectation [of privacy] will
depend on what the legal rule is”).
To address this circularity problem, the Court has in
sisted that expectations of privacy must come from outside
its Fourth Amendment precedents, “either by reference to
concepts of real or personal property law or to understand
ings that are recognized and permitted by society.” Rakas
v. Illinois, 439 U. S. 128, 144, n. 12 (1978). But the
Court’s supposed reliance on “real or personal property
law” rings hollow. The whole point of Katz was to “ ‘dis
credi[t]’ ” the relationship between the Fourth Amendment
and property law, 389 U. S., at 353, and this Court has
repeatedly downplayed the importance of property law
under the Katz test, see, e.g., United States v. Salvucci,
448 U. S. 83, 91 (1980) (“[P]roperty rights are neither the
beginning nor the end of this Court’s inquiry [under
Katz]”); Rawlings v. Kentucky, 448 U. S. 98, 105 (1980)
(“[This Court has] emphatically rejected the notion that
‘arcane’ concepts of property law ought to control the
ability to claim the protections of the Fourth Amend
ment”). Today, for example, the Court makes no mention
of property law, except to reject its relevance. See ante, at
5, and n. 1.
As for “understandings that are recognized or permitted
in society,” this Court has never answered even the most
basic questions about what this means. See Kerr, Four
20 CARPENTER v. UNITED STATES
THOMAS, J., dissenting
Models of Fourth Amendment Protection, 60 Stan. L. Rev.
503, 504–505 (2007). For example, our precedents do not
explain who is included in “society,” how we know what
they “recogniz[e] or permi[t],” and how much of society must
agree before something constitutes an “understanding.”
Here, for example, society might prefer a balanced
regime that prohibits the Government from obtaining cell-
site location information unless it can persuade a neutral
magistrate that the information bears on an ongoing
criminal investigation. That is precisely the regime Con
gress created under the Stored Communications Act and
Telecommunications Act. See 47 U. S. C. §222(c)(1); 18
U. S. C. §§2703(c)(1)(B), (d). With no sense of irony, the
Court invalidates this regime today—the one that society
actually created “in the form of its elected representatives
in Congress.” 819 F. 3d 880, 890 (2016).
Truth be told, this Court does not treat the Katz test as
a descriptive inquiry. Although the Katz test is phrased in
descriptive terms about society’s views, this Court treats it
like a normative question—whether a particular practice
should be considered a search under the Fourth Amend
ment. Justice Harlan thought this was the best way to
understand his test. See White, 401 U. S., at 786 (dissent
ing opinion) (explaining that courts must assess the “de
sirability” of privacy expectations and ask whether courts
“should” recognize them by “balanc[ing]” the “impact on
the individual’s sense of security . . . against the utility of
the conduct as a technique of law enforcement”). And a
normative understanding is the only way to make sense of
this Court’s precedents, which bear the hallmarks of sub
jective policymaking instead of neutral legal decisionmak
ing. “[T]he only thing the past three decades have estab
lished about the Katz test” is that society’s expectations of
privacy “bear an uncanny resemblance to those expecta
tions of privacy that this Court considers reasonable.”
Cite as: 585 U. S. ____ (2018) 21
THOMAS, J., dissenting
Carter, 525 U. S., at 97 (opinion of Scalia, J.). Yet,
“[t]hough we know ourselves to be eminently reasonable,
self-awareness of eminent reasonableness is not really a
substitute for democratic election.” Sosa v. Alvarez-
Machain, 542 U. S. 692, 750 (2004) (Scalia, J., concurring
in part and concurring in judgment).
* * *
In several recent decisions, this Court has declined to
apply the Katz test because it threatened to narrow the
original scope of the Fourth Amendment. See Grady v.
North Carolina, 575 U. S. ___, ___ (2015) (per curiam) (slip
op., at 3); Florida v. Jardines, 569 U. S. 1, 5 (2013); Jones,
565 U. S., at 406–407. But as today’s decision demon
strates, Katz can also be invoked to expand the Fourth
Amendment beyond its original scope. This Court should
not tolerate errors in either direction. “The People,
through ratification, have already weighed the policy
tradeoffs that constitutional rights entail.” Luis v. United
States, 578 U. S. ___, ___ (2016) (THOMAS, J., concurring in
judgment) (slip op., at 10). Whether the rights they rati
fied are too broad or too narrow by modern lights, this
Court has no authority to unilaterally alter the document
they approved.
Because the Katz test is a failed experiment, this Court
is dutybound to reconsider it. Until it does, I agree with
my dissenting colleagues’ reading of our precedents.
Accordingly, I respectfully dissent.
Cite as: 585 U. S. ____ (2018) 1
ALITO, J., dissenting
SUPREME COURT OF THE UNITED STATES
_________________
No. 16–402
_________________
TIMOTHY IVORY CARPENTER, PETITIONER v.
UNITED STATES
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE SIXTH CIRCUIT
[June 22, 2018]
JUSTICE ALITO, with whom JUSTICE THOMAS joins,
dissenting.
I share the Court’s concern about the effect of new tech-
nology on personal privacy, but I fear that today’s decision
will do far more harm than good. The Court’s reasoning
fractures two fundamental pillars of Fourth Amendment
law, and in doing so, it guarantees a blizzard of litigation
while threatening many legitimate and valuable investiga-
tive practices upon which law enforcement has rightfully
come to rely.
First, the Court ignores the basic distinction between an
actual search (dispatching law enforcement officers to
enter private premises and root through private papers
and effects) and an order merely requiring a party to look
through its own records and produce specified documents.
The former, which intrudes on personal privacy far more
deeply, requires probable cause; the latter does not.
Treating an order to produce like an actual search, as
today’s decision does, is revolutionary. It violates both the
original understanding of the Fourth Amendment and
more than a century of Supreme Court precedent. Unless
it is somehow restricted to the particular situation in the
present case, the Court’s move will cause upheaval. Must
every grand jury subpoena duces tecum be supported by
probable cause? If so, investigations of terrorism, political
2 CARPENTER v. UNITED STATES
ALITO, J., dissenting
corruption, white-collar crime, and many other offenses
will be stymied. And what about subpoenas and other
document-production orders issued by administrative
agencies? See, e.g., 15 U. S. C. §57b–1(c) (Federal Trade
Commission); §§77s(c), 78u(a)–(b) (Securities and Ex-
change Commission); 29 U. S. C. §657(b) (Occupational
Safety and Health Administration); 29 CFR §1601.16(a)(2)
(2017) (Equal Employment Opportunity Commission).
Second, the Court allows a defendant to object to the
search of a third party’s property. This also is revolution-
ary. The Fourth Amendment protects “[t]he right of the
people to be secure in their persons, houses, papers, and
effects” (emphasis added), not the persons, houses, papers,
and effects of others. Until today, we have been careful to
heed this fundamental feature of the Amendment’s text.
This was true when the Fourth Amendment was tied to
property law, and it remained true after Katz v. United
States, 389 U. S. 347 (1967), broadened the Amendment’s
reach.
By departing dramatically from these fundamental
principles, the Court destabilizes long-established Fourth
Amendment doctrine. We will be making repairs—or
picking up the pieces—for a long time to come.
I
Today the majority holds that a court order requiring
the production of cell-site records may be issued only after
the Government demonstrates probable cause. See ante,
at 18. That is a serious and consequential mistake. The
Court’s holding is based on the premise that the order
issued in this case was an actual “search” within the
meaning of the Fourth Amendment, but that premise is
inconsistent with the original meaning of the Fourth
Amendment and with more than a century of precedent.
Cite as: 585 U. S. ____ (2018)
3
ALITO, J., dissenting
A
The order in this case was the functional equivalent of a
subpoena for documents, and there is no evidence that
these writs were regarded as “searches” at the time of the
founding. Subpoenas duces tecum and other forms of
compulsory document production were well known to the
founding generation. Blackstone dated the first writ of
subpoena to the reign of King Richard II in the late 14th
century, and by the end of the 15th century, the use of
such writs had “become the daily practice of the [Chan-
cery] court.” 3 W. Blackstone, Commentaries on the Laws
of England 53 (G. Tucker ed. 1803) (Blackstone). Over the
next 200 years, subpoenas would grow in prominence and
power in tandem with the Court of Chancery, and by the
end of Charles II’s reign in 1685, two important innova-
tions had occurred.
First, the Court of Chancery developed a new species of
subpoena. Until this point, subpoenas had been used
largely to compel attendance and oral testimony from
witnesses; these subpoenas correspond to today’s subpoe-
nas ad testificandum. But the Court of Chancery also
improvised a new version of the writ that tacked onto a
regular subpoena an order compelling the witness to bring
certain items with him. By issuing these so-called sub-
poenas duces tecum, the Court of Chancery could compel
the production of papers, books, and other forms of physi-
cal evidence, whether from the parties to the case or from
third parties. Such subpoenas were sufficiently common-
place by 1623 that a leading treatise on the practice of law
could refer in passing to the fee for a “Sub pœna of Ducas
tecum” (seven shillings and two pence) without needing to
elaborate further. T. Powell, The Attourneys Academy 79
(1623). Subpoenas duces tecum would swell in use over
the next century as the rules for their application became
ever more developed and definite. See, e.g., 1 G. Jacob,
The Compleat Chancery-Practiser 290 (1730) (“The Sub-
4 CARPENTER v. UNITED STATES
ALITO, J., dissenting
poena duces tecum is awarded when the Defendant has
confessed by his Answer that he hath such Writings in his
Hands as are prayed by the Bill to be discovered or
brought into Court”).
Second, although this new species of subpoena had its
origins in the Court of Chancery, it soon made an appear-
ance in the work of the common-law courts as well. One
court later reported that “[t]he Courts of Common law . . .
employed the same or similar means . . . from the time of
Charles the Second at least.” Amey v. Long, 9 East. 473,
484, 103 Eng. Rep. 653, 658 (K. B. 1808).
By the time Blackstone published his Commentaries on
the Laws of England in the 1760’s, the use of subpoenas
duces tecum had bled over substantially from the courts of
equity to the common-law courts. Admittedly, the transi-
tion was still incomplete: In the context of jury trials, for
example, Blackstone complained about “the want of a
compulsive power for the production of books and papers
belonging to the parties.” Blackstone 381; see also, e.g.,
Entick v. Carrington, 19 State Trials 1029, 1073 (K. B.
1765) (“I wish some cases had been shewn, where the law
forceth evidence out of the owner’s custody by process.
[But] where the adversary has by force or fraud got pos-
session of your own proper evidence, there is no way to get
it back but by action”). But Blackstone found some com-
fort in the fact that at least those documents “[i]n the
hands of third persons . . . can generally be obtained by
rule of court, or by adding a clause of requisition to the
writ of subpoena, which is then called a subpoena duces
tecum.” Blackstone 381; see also, e.g., Leeds v. Cook, 4
Esp. 256, 257, 170 Eng. Rep. 711 (N. P. 1803) (third-party
subpoena duces tecum); Rex v. Babb, 3 T. R. 579, 580, 100
Eng. Rep. 743, 744 (K. B. 1790) (third-party document
production). One of the primary questions outstanding,
then, was whether common-law courts would remedy the
“defect[s]” identified by the Commentaries, and allow
Cite as: 585 U. S. ____ (2018) 5
ALITO, J., dissenting
parties to use subpoenas duces tecum not only with respect
to third parties but also with respect to each other. Black-
stone 381.
That question soon found an affirmative answer on both
sides of the Atlantic. In the United States, the First Con-
gress established the federal court system in the Judiciary
Act of 1789. As part of that Act, Congress authorized “all
the said courts of the United States . . . in the trial of
actions at law, on motion and due notice thereof being
given, to require the parties to produce books or writings
in their possession or power, which contain evidence per-
tinent to the issue, in cases and under circumstances
where they might be compelled to produce the same by the
ordinary rules of proceeding in chancery.” §15, 1 Stat. 82.
From that point forward, federal courts in the United
States could compel the production of documents regard-
less of whether those documents were held by parties to
the case or by third parties.
In Great Britain, too, it was soon definitively estab-
lished that common-law courts, like their counterparts in
equity, could subpoena documents held either by parties to
the case or by third parties. After proceeding in fits and
starts, the King’s Bench eventually held in Amey v. Long
that the “writ of subpœna duces tecum [is] a writ of com-
pulsory obligation and effect in the law.” 9 East., at 486,
103 Eng. Rep., at 658. Writing for a unanimous court,
Lord Chief Justice Ellenborough explained that “[t]he
right to resort to means competent to compel the produc-
tion of written, as well as oral, testimony seems essential
to the very existence and constitution of a Court of Com-
mon Law.” Id., at 484, 103 Eng. Rep., at 658. Without the
power to issue subpoenas duces tecum, the Lord Chief
Justice observed, common-law courts “could not possibly
proceed with due effect.” Ibid.
The prevalence of subpoenas duces tecum at the time of
the founding was not limited to the civil context. In crim-
6 CARPENTER v. UNITED STATES
ALITO, J., dissenting
inal cases, courts and prosecutors were also using the writ
to compel the production of necessary documents. In Rex
v. Dixon, 3 Burr. 1687, 97 Eng. Rep. 1047 (K. B. 1765), for
example, the King’s Bench considered the propriety of a
subpoena duces tecum served on an attorney named Sam-
uel Dixon. Dixon had been called “to give evidence before
the grand jury of the county of Northampton” and specifi-
cally “to produce three vouchers . . . in order to found a
prosecution by way of indictment against [his client]
Peach . . . for forgery.” Id., at 1687, 97 Eng. Rep., at 1047–
1048. Although the court ultimately held that Dixon had
not needed to produce the vouchers on account of attorney-
client privilege, none of the justices expressed the slightest
doubt about the general propriety of subpoenas duces
tecum in the criminal context. See id., at 1688, 97 Eng.
Rep., at 1048. As Lord Chief Justice Ellenborough later
explained, “[i]n that case no objection was taken to the
writ, but to the special circumstances under which the
party possessed the papers; so that the Court may be
considered as recognizing the general obligation to obey
writs of that description in other cases.” Amey, supra, at
485, 103 Eng. Rep., at 658; see also 4 J. Chitty, Practical
Treatise on the Criminal Law 185 (1816) (template for
criminal subpoena duces tecum).
As Dixon shows, subpoenas duces tecum were routine in
part because of their close association with grand juries.
Early American colonists imported the grand jury, like so
many other common-law traditions, and they quickly
flourished. See United States v. Calandra, 414 U. S. 338,
342–343 (1974). Grand juries were empaneled by the
federal courts almost as soon as the latter were estab-
lished, and both they and their state counterparts actively
exercised their wide-ranging common-law authority. See
R. Younger, The People’s Panel 47–55 (1963). Indeed, “the
Founders thought the grand jury so essential . . . that they
provided in the Fifth Amendment that federal prosecution
Cite as: 585 U. S. ____ (2018) 7
ALITO, J., dissenting
for serious crimes can only be instituted by ‘a presentment
or indictment of a Grand Jury.’ ” Calandra, supra, at 343.
Given the popularity and prevalence of grand juries at
the time, the Founders must have been intimately familiar
with the tools they used—including compulsory process—
to accomplish their work. As a matter of tradition, grand
juries were “accorded wide latitude to inquire into viola-
tions of criminal law,” including the power to “compel the
production of evidence or the testimony of witnesses as
[they] conside[r] appropriate.” Ibid. Long before national
independence was achieved, grand juries were already
using their broad inquisitorial powers not only to present
and indict criminal suspects but also to inspect public
buildings, to levy taxes, to supervise the administration of
the laws, to advance municipal reforms such as street
repair and bridge maintenance, and in some cases even to
propose legislation. Younger, supra, at 5–26. Of course,
such work depended entirely on grand juries’ ability to
access any relevant documents.
Grand juries continued to exercise these broad inquisi-
torial powers up through the time of the founding. See
Blair v. United States, 250 U. S. 273, 280 (1919) (“At the
foundation of our Federal Government the inquisitorial
function of the grand jury and the compulsion of witnesses
were recognized as incidents of the judicial power”). In a
series of lectures delivered in the early 1790’s, Justice
James Wilson crowed that grand juries were “the peculiar
boast of the common law” thanks in part to their wide-
ranging authority: “All the operations of government, and
of its ministers and officers, are within the compass of
their view and research.” 2 J. Wilson, The Works of James
Wilson 534, 537 (R. McCloskey ed. 1967). That reflected
the broader insight that “[t]he grand jury’s investigative
power must be broad if its public responsibility is ade-
quately to be discharged.” Calandra, supra, at 344.
Compulsory process was also familiar to the founding
8 CARPENTER v. UNITED STATES
ALITO, J., dissenting
generation in part because it reflected “the ancient propo-
sition of law” that “ ‘ “the public . . . has a right to every
man’s evidence.” ’ ” United States v. Nixon, 418 U. S. 683,
709 (1974); see also ante, at 10 (KENNEDY, J., dissenting).
As early as 1612, “Lord Bacon is reported to have declared
that ‘all subjects, without distinction of degrees, owe to the
King tribute and service, not only of their deed and hand,
but of their knowledge and discovery.’ ” Blair, supra, at
279–280. That duty could be “onerous at times,” yet the
Founders considered it “necessary to the administration of
justice according to the forms and modes established in
our system of government.” Id., at 281; see also Calandra,
supra, at 345.
B
Talk of kings and common-law writs may seem out of
place in a case about cell-site records and the protections
afforded by the Fourth Amendment in the modern age.
But this history matters, not least because it tells us what
was on the minds of those who ratified the Fourth
Amendment and how they understood its scope. That
history makes it abundantly clear that the Fourth
Amendment, as originally understood, did not apply to the
compulsory production of documents at all.
The Fourth Amendment does not regulate all methods
by which the Government obtains documents. Rather, it
prohibits only those “searches and seizures” of “persons,
houses, papers, and effects” that are “unreasonable.”
Consistent with that language, “at least until the latter
half of the 20th century” “our Fourth Amendment juris-
prudence was tied to common-law trespass.” United
States v. Jones, 565 U. S. 400, 405 (2012). So by its terms,
the Fourth Amendment does not apply to the compulsory
production of documents, a practice that involves neither
any physical intrusion into private space nor any taking of
property by agents of the state. Even Justice Brandeis—a
Cite as: 585 U. S. ____ (2018) 9
ALITO, J., dissenting
stalwart proponent of construing the Fourth Amendment
liberally—acknowledged that “under any ordinary con-
struction of language,” “there is no ‘search’ or ‘seizure’
when a defendant is required to produce a document in
the orderly process of a court’s procedure.” Olmstead v.
United States, 277 U. S. 438, 476 (1928) (dissenting
opinion).1
Nor is there any reason to believe that the Founders
intended the Fourth Amendment to regulate courts’ use of
compulsory process. American colonists rebelled against
the Crown’s physical invasions of their persons and their
property, not against its acquisition of information by any
and all means. As Justice Black once put it, “[t]he Fourth
Amendment was aimed directly at the abhorred practice of
breaking in, ransacking and searching homes and other
buildings and seizing people’s personal belongings without
warrants issued by magistrates.” Katz, 389 U. S., at 367
(dissenting opinion). More recently, we have acknowl-
edged that “the Fourth Amendment was the founding
generation’s response to the reviled ‘general warrants’ and
‘writs of assistance’ of the colonial era, which allowed
——————
1 Any other interpretation of the Fourth Amendment’s text would run
into insuperable problems because it would apply not only to subpoenas
duces tecum but to all other forms of compulsory process as well. If the
Fourth Amendment applies to the compelled production of documents,
then it must also apply to the compelled production of testimony—an
outcome that we have repeatedly rejected and which, if accepted, would
send much of the field of criminal procedure into a tailspin. See, e.g.,
United States v. Dionisio, 410 U. S. 1, 9 (1973) (“It is clear that a
subpoena to appear before a grand jury is not a ‘seizure’ in the Fourth
Amendment sense, even though that summons may be inconvenient or
burdensome”); United States v. Calandra, 414 U. S. 338, 354 (1974)
(“Grand jury questions . . . involve no independent governmental
invasion of one’s person, house, papers, or effects”). As a matter of
original understanding, a subpoena duces tecum no more effects a
“search” or “seizure” of papers within the meaning of the Fourth
Amendment than a subpoena ad testificandum effects a “search” or
“seizure” of a person.
10 CARPENTER v. UNITED STATES
ALITO, J., dissenting
British officers to rummage through homes in an unre-
strained search for evidence of criminal activity.” Riley v.
California, 573 U. S. ___, ___ (2014) (slip op., at 27).
General warrants and writs of assistance were noxious
not because they allowed the Government to acquire
evidence in criminal investigations, but because of the
means by which they permitted the Government to acquire
that evidence. Then, as today, searches could be quite
invasive. Searches generally begin with officers “mak[ing]
nonconsensual entries into areas not open to the public.”
Donovan v. Lone Steer, Inc., 464 U. S. 408, 414 (1984).
Once there, officers are necessarily in a position to observe
private spaces generally shielded from the public and
discernible only with the owner’s consent. Private area
after private area becomes exposed to the officers’ eyes as
they rummage through the owner’s property in their hunt
for the object or objects of the search. If they are search-
ing for documents, officers may additionally have to rifle
through many other papers—potentially filled with the
most intimate details of a person’s thoughts and life—
before they find the specific information they are seeking.
See Andresen v. Maryland, 427 U. S. 463, 482, n. 11
(1976). If anything sufficiently incriminating comes into
view, officers seize it. Horton v. California, 496 U. S. 128,
136–137 (1990). Physical destruction always lurks as an
underlying possibility; “officers executing search warrants
on occasion must damage property in order to perform
their duty.” Dalia v. United States, 441 U. S. 238, 258
(1979); see, e.g., United States v. Ramirez, 523 U. S. 65,
71–72 (1998) (breaking garage window); United States v.
Ross, 456 U. S. 798, 817–818 (1982) (ripping open car
upholstery); Brown v. Battle Creek Police Dept., 844 F. 3d
556, 572 (CA6 2016) (shooting and killing two pet dogs);
Lawmaster v. Ward, 125 F. 3d 1341, 1350, n. 3 (CA10
1997) (breaking locks).
Compliance with a subpoena duces tecum requires none
Cite as: 585 U. S. ____ (2018) 11
ALITO, J., dissenting
of that. A subpoena duces tecum permits a subpoenaed
individual to conduct the search for the relevant docu-
ments himself, without law enforcement officers entering
his home or rooting through his papers and effects. As a
result, subpoenas avoid the many incidental invasions of
privacy that necessarily accompany any actual search.
And it was those invasions of privacy—which, although
incidental, could often be extremely intrusive and damag-
ing—that led to the adoption of the Fourth Amendment.
Neither this Court nor any of the parties have offered
the slightest bit of historical evidence to support the idea
that the Fourth Amendment originally applied to subpoe-
nas duces tecum and other forms of compulsory process.
That is telling, for as I have explained, these forms of
compulsory process were a feature of criminal (and civil)
procedure well known to the Founders. The Founders
would thus have understood that holding the compulsory
production of documents to the same standard as actual
searches and seizures would cripple the work of courts in
civil and criminal cases alike. It would be remarkable to
think that, despite that knowledge, the Founders would
have gone ahead and sought to impose such a require-
ment. It would be even more incredible to believe that the
Founders would have imposed that requirement through
the inapt vehicle of an amendment directed at different
concerns. But it would blink reality entirely to argue that
this entire process happened without anyone saying the
least thing about it—not during the drafting of the Bill of
Rights, not during any of the subsequent ratification
debates, and not for most of the century that followed. If
the Founders thought the Fourth Amendment applied to
the compulsory production of documents, one would imag-
ine that there would be some founding-era evidence of the
Fourth Amendment being applied to the compulsory pro-
duction of documents. Cf. Free Enterprise Fund v. Public
Company Accounting Oversight Bd., 561 U. S. 477, 505
12 CARPENTER v. UNITED STATES
ALITO, J., dissenting
(2010); Printz v. United States, 521 U. S. 898, 905 (1997).
Yet none has been brought to our attention.
C
Of course, our jurisprudence has not stood still since
1791. We now evaluate subpoenas duces tecum and other
forms of compulsory document production under the
Fourth Amendment, although we employ a reasonableness
standard that is less demanding than the requirements for
a warrant. But the road to that doctrinal destination was
anything but smooth, and our initial missteps—and the
subsequent struggle to extricate ourselves from their
consequences—should provide an object lesson for today’s
majority about the dangers of holding compulsory process
to the same standard as actual searches and seizures.
For almost a century after the Fourth Amendment was
enacted, this Court said and did nothing to indicate that it
might regulate the compulsory production of documents.
But that changed temporarily when the Court decided
Boyd v. United States, 116 U. S. 616 (1886), the first—and,
until today, the only—case in which this Court has ever
held the compulsory production of documents to the same
standard as actual searches and seizures.
The Boyd Court held that a court order compelling a
company to produce potentially incriminating business
records violated both the Fourth and the Fifth Amend-
ments. The Court acknowledged that “certain aggravating
incidents of actual search and seizure, such as forcible
entry into a man’s house and searching amongst his pa-
pers, are wanting” when the Government relies on com-
pulsory process. Id., at 622. But it nevertheless asserted
that the Fourth Amendment ought to “be liberally con-
strued,” id., at 635, and further reasoned that compulsory
process “effects the sole object and purpose of search and
seizure” by “forcing from a party evidence against him-
self,” id., at 622. “In this regard,” the Court concluded,
Cite as: 585 U. S. ____ (2018) 13
ALITO, J., dissenting
“the Fourth and Fifth Amendments run almost into each
other.” Id., at 630. Having equated compulsory process
with actual searches and seizures and having melded the
Fourth Amendment with the Fifth, the Court then found
the order at issue unconstitutional because it compelled
the production of property to which the Government did
not have superior title. See id., at 622–630.
In a concurrence joined by Chief Justice Waite, Justice
Miller agreed that the order violated the Fifth Amend-
ment, id., at 639, but he strongly protested the majority’s
invocation of the Fourth Amendment. He explained:
“[T]here is no reason why this court should assume that
the action of the court below, in requiring a party to pro-
duce certain papers . . . , authorizes an unreasonable
search or seizure of the house, papers, or effects of that
party. There is in fact no search and no seizure.” Ibid. “If
the mere service of a notice to produce a paper . . . is a
search,” Justice Miller concluded, “then a change has
taken place in the meaning of words, which has not come
within my reading, and which I think was unknown at the
time the Constitution was made.” Id., at 641.
Although Boyd was replete with stirring rhetoric, its
reasoning was confused from start to finish in a way that
ultimately made the decision unworkable. See 3 W.
LaFave, J. Israel, N. King, & O. Kerr, Criminal Procedure
§8.7(a) (4th ed. 2015). Over the next 50 years, the Court
would gradually roll back Boyd’s erroneous conflation of
compulsory process with actual searches and seizures.
That effort took its first significant stride in Hale v.
Henkel, 201 U. S. 43 (1906), where the Court found it
“quite clear” and “conclusive” that “the search and seizure
clause of the Fourth Amendment was not intended to
interfere with the power of courts to compel, through a
subpœna duces tecum, the production, upon a trial in
court, of documentary evidence.” Id., at 73. Without that
writ, the Court recognized, “it would be ‘utterly impossible
14 CARPENTER v. UNITED STATES
ALITO, J., dissenting
to carry on the administration of justice.’ ” Ibid.
Hale, however, did not entirely liberate subpoenas
duces tecum from Fourth Amendment constraints. While
refusing to treat such subpoenas as the equivalent of
actual searches, Hale concluded that they must not be
unreasonable. And it held that the subpoena duces tecum
at issue was “far too sweeping in its terms to be regarded
as reasonable.” Id., at 76. The Hale Court thus left two
critical questions unanswered: Under the Fourth Amend-
ment, what makes the compulsory production of docu-
ments “reasonable,” and how does that standard differ
from the one that governs actual searches and seizures?
The Court answered both of those questions definitively
in Oklahoma Press Publishing Co. v. Walling, 327 U. S.
186 (1946), where we held that the Fourth Amendment
regulates the compelled production of documents, but less
stringently than it does full-blown searches and seizures.
Oklahoma Press began by admitting that the Court’s
opinions on the subject had “perhaps too often . . . been
generative of heat rather than light,” “mov[ing] with vari-
ant direction” and sometimes having “highly contrasting”
“emphasis and tone.” Id., at 202. “The primary source of
misconception concerning the Fourth Amendment’s func-
tion” in this context, the Court explained, “lies perhaps in
the identification of cases involving so-called ‘figurative’ or
‘constructive’ search with cases of actual search and sei-
zure.” Ibid. But the Court held that “the basic distinc-
tion” between the compulsory production of documents on
the one hand, and actual searches and seizures on the
other, meant that two different standards had to be ap-
plied. Id., at 204.
Having reversed Boyd’s conflation of the compelled
production of documents with actual searches and sei-
zures, the Court then set forth the relevant Fourth
Amendment standard for the former. When it comes to
“the production of corporate or other business records,” the
Cite as: 585 U. S. ____ (2018) 15
ALITO, J., dissenting
Court held that the Fourth Amendment “at the most
guards against abuse only by way of too much indefinite-
ness or breadth in the things required to be ‘particularly
described,’ if also the inquiry is one the demanding agency
is authorized by law to make and the materials specified
are relevant.” Oklahoma Press, supra, at 208. Notably,
the Court held that a showing of probable cause was not
necessary so long as “the investigation is authorized by
Congress, is for a purpose Congress can order, and the
documents sought are relevant to the inquiry.” Id., at 209.
Since Oklahoma Press, we have consistently hewed to
that standard. See, e.g., Lone Steer, Inc., 464 U. S., at
414–415; United States v. Miller, 425 U. S. 435, 445–446
(1976); California Bankers Assn. v. Shultz, 416 U. S. 21,
67 (1974); United States v. Dionisio, 410 U. S. 1, 11–12
(1973); See v. Seattle, 387 U. S. 541, 544 (1967); United
States v. Powell, 379 U. S. 48, 57–58 (1964); McPhaul v.
United States, 364 U. S. 372, 382–383 (1960); United
States v. Morton Salt Co., 338 U. S. 632, 652–653 (1950);
cf. McLane Co. v. EEOC, 581 U. S. ___, ___ (2017) (slip op.,
at 11). By applying Oklahoma Press and thereby respect-
ing “the traditional distinction between a search warrant
and a subpoena,” Miller, supra, at 446, this Court has
reinforced “the basic compromise” between “the public
interest” in every man’s evidence and the private interest
“of men to be free from officious meddling.” Oklahoma
Press, supra, at 213.
D
Today, however, the majority inexplicably ignores the
settled rule of Oklahoma Press in favor of a resurrected
version of Boyd. That is mystifying. This should have
been an easy case regardless of whether the Court looked
to the original understanding of the Fourth Amendment or
to our modern doctrine.
As a matter of original understanding, the Fourth
16 CARPENTER v. UNITED STATES
ALITO, J., dissenting
Amendment does not regulate the compelled production of
documents at all. Here the Government received the
relevant cell-site records pursuant to a court order compel-
ling Carpenter’s cell service provider to turn them over.
That process is thus immune from challenge under the
original understanding of the Fourth Amendment.
As a matter of modern doctrine, this case is equally
straightforward. As JUSTICE KENNEDY explains, no
search or seizure of Carpenter or his property occurred in
this case. Ante, at 6–22; see also Part II, infra. But even
if the majority were right that the Government “searched”
Carpenter, it would at most be a “figurative or construc-
tive search” governed by the Oklahoma Press standard,
not an “actual search” controlled by the Fourth Amend-
ment’s warrant requirement.
And there is no doubt that the Government met the
Oklahoma Press standard here. Under Oklahoma Press, a
court order must “ ‘be sufficiently limited in scope, relevant
in purpose, and specific in directive so that compliance will
not be unreasonably burdensome.’ ” Lone Steer, Inc.,
supra, at 415. Here, the type of order obtained by the
Government almost necessarily satisfies that standard.
The Stored Communications Act allows a court to issue
the relevant type of order “only if the governmental entity
offers specific and articulable facts showing that there are
reasonable grounds to believe that . . . the records . . .
sough[t] are relevant and material to an ongoing criminal
investigation.” 18 U. S. C. §2703(d). And the court “may
quash or modify such order” if the provider objects that
the “records requested are unusually voluminous in na-
ture or compliance with such order otherwise would cause
an undue burden on such provider.” Ibid. No such objec-
tion was made in this case, and Carpenter does not sug-
gest that the orders contravened the Oklahoma Press
standard in any other way.
That is what makes the majority’s opinion so puzzling.
Cite as: 585 U. S. ____ (2018) 17
ALITO, J., dissenting
It decides that a “search” of Carpenter occurred within the
meaning of the Fourth Amendment, but then it leaps
straight to imposing requirements that—until this point—
have governed only actual searches and seizures. See
ante, at 18–19. Lost in its race to the finish is any real
recognition of the century’s worth of precedent it jeopard-
izes. For the majority, this case is apparently no different
from one in which Government agents raided Carpenter’s
home and removed records associated with his cell phone.
Against centuries of precedent and practice, all that the
Court can muster is the observation that “this Court has
never held that the Government may subpoena third
parties for records in which the suspect has a reasonable
expectation of privacy.” Ante, at 19. Frankly, I cannot
imagine a concession more damning to the Court’s argu-
ment than that. As the Court well knows, the reason that
we have never seen such a case is because—until today—
defendants categorically had no “reasonable expectation of
privacy” and no property interest in records belonging to
third parties. See Part II, infra. By implying otherwise,
the Court tries the nice trick of seeking shelter under the
cover of precedents that it simultaneously perforates.
Not only that, but even if the Fourth Amendment per-
mitted someone to object to the subpoena of a third party’s
records, the Court cannot explain why that individual
should be entitled to greater Fourth Amendment protec-
tion than the party actually being subpoenaed. When
parties are subpoenaed to turn over their records, after all,
they will at most receive the protection afforded by Okla-
homa Press even though they will own and have a reason-
able expectation of privacy in the records at issue. Under
the Court’s decision, however, the Fourth Amendment will
extend greater protections to someone else who is not
being subpoenaed and does not own the records. That
outcome makes no sense, and the Court does not even
attempt to defend it.
18 CARPENTER v. UNITED STATES
ALITO, J., dissenting
We have set forth the relevant Fourth Amendment
standard for subpoenaing business records many times
over. Out of those dozens of cases, the majority cannot
find even one that so much as suggests an exception to the
Oklahoma Press standard for sufficiently personal infor-
mation. Instead, we have always “described the constitu-
tional requirements” for compulsory process as being
“ ‘settled’ ” and as applying categorically to all “ ‘subpoenas
[of] corporate books or records.’ ” Lone Steer, Inc., 464
U. S., at 415 (internal quotation marks omitted). That
standard, we have held, is “the most” protection the
Fourth Amendment gives “to the production of corporate
records and papers.” Oklahoma Press, 327 U. S., at 208
(emphasis added).2
Although the majority announces its holding in the
context of the Stored Communications Act, nothing stops
its logic from sweeping much further. The Court has
offered no meaningful limiting principle, and none is
apparent. Cf. Tr. of Oral Arg. 31 (Carpenter’s counsel
admitting that “a grand jury subpoena . . . would be held
to the same standard as any other subpoena or subpoena-
like request for [cell-site] records”).
Holding that subpoenas must meet the same standard
as conventional searches will seriously damage, if not
destroy, their utility. Even more so than at the founding,
today the Government regularly uses subpoenas duces
tecum and other forms of compulsory process to carry out
its essential functions. See, e.g., Dionisio, 410 U. S., at
11–12 (grand jury subpoenas); McPhaul, 364 U. S., at
382–383 (legislative subpoenas); Oklahoma Press, supra,
at 208–209 (administrative subpoenas). Grand juries, for
——————
2 All that the Court can say in response is that we have “been careful
not to uncritically extend existing precedents” when confronting new
technologies. Ante, at 20. But applying a categorical rule categorically
does not “extend” precedent, so the Court’s statement ends up sounding
a lot like a tacit admission that it is overruling our precedents.
Cite as: 585 U. S. ____ (2018) 19
ALITO, J., dissenting
example, have long “compel[led] the production of evi-
dence” in order to determine “whether there is probable
cause to believe a crime has been committed.” Calandra,
414 U. S., at 343 (emphasis added). Almost by definition,
then, grand juries will be unable at first to demonstrate
“the probable cause required for a warrant.” Ante, at 19
(majority opinion); see also Oklahoma Press, supra, at 213.
If they are required to do so, the effects are as predictable
as they are alarming: Many investigations will sputter out
at the start, and a host of criminals will be able to evade
law enforcement’s reach.
“To ensure that justice is done, it is imperative to the
function of courts that compulsory process be available for
the production of evidence.” Nixon, 418 U. S., at 709. For
over a hundred years, we have understood that holding
subpoenas to the same standard as actual searches and
seizures “would stop much if not all of investigation in the
public interest at the threshold of inquiry.” Oklahoma
Press, supra, at 213. Today a skeptical majority decides to
put that understanding to the test.
II
Compounding its initial error, the Court also holds that
a defendant has the right under the Fourth Amendment to
object to the search of a third party’s property. This hold-
ing flouts the clear text of the Fourth Amendment, and it
cannot be defended under either a property-based inter-
pretation of that Amendment or our decisions applying the
reasonable-expectations-of-privacy test adopted in Katz,
389 U. S. 347. By allowing Carpenter to object to the
search of a third party’s property, the Court threatens to
revolutionize a second and independent line of Fourth
Amendment doctrine.
A
It bears repeating that the Fourth Amendment guaran-
20 CARPENTER v. UNITED STATES
ALITO, J., dissenting
tees “[t]he right of the people to be secure in their persons,
houses, papers, and effects.” (Emphasis added.) The
Fourth Amendment does not confer rights with respect to
the persons, houses, papers, and effects of others. Its
language makes clear that “Fourth Amendment rights are
personal,” Rakas v. Illinois, 439 U. S. 128, 140 (1978), and
as a result, this Court has long insisted that they “may not
be asserted vicariously,” id., at 133. It follows that a
“person who is aggrieved . . . only through the introduction
of damaging evidence secured by a search of a third per-
son’s premises or property has not had any of his Fourth
Amendment rights infringed.” Id., at 134.
In this case, as JUSTICE KENNEDY cogently explains, the
cell-site records obtained by the Government belong to
Carpenter’s cell service providers, not to Carpenter. See
ante, at 12–13. Carpenter did not create the cell-site
records. Nor did he have possession of them; at all rele-
vant times, they were kept by the providers. Once Car-
penter subscribed to his provider’s service, he had no right
to prevent the company from creating or keeping the
information in its records. Carpenter also had no right to
demand that the providers destroy the records, no right to
prevent the providers from destroying the records, and,
indeed, no right to modify the records in any way whatso-
ever (or to prevent the providers from modifying the rec-
ords). Carpenter, in short, has no meaningful control over
the cell-site records, which are created, maintained, al-
tered, used, and eventually destroyed by his cell service
providers.
Carpenter responds by pointing to a provision of the
Telecommunications Act that requires a provider to dis-
close cell-site records when a customer so requests. See 47
U. S. C. §222(c)(2). But a statutory disclosure requirement
is hardly sufficient to give someone an ownership interest
in the documents that must be copied and disclosed.
Many statutes confer a right to obtain copies of documents
Cite as: 585 U. S. ____ (2018) 21
ALITO, J., dissenting
without creating any property right.3
Carpenter’s argument is particularly hard to swallow
because nothing in the Telecommunications Act precludes
cell service providers from charging customers a fee for
accessing cell-site records. See ante, at 12–13 (KENNEDY,
J., dissenting). It would be very strange if the owner of
records were required to pay in order to inspect his own
——————
3 See, e.g., Freedom of Information Act, 5 U. S. C. §552(a) (“Each
agency shall make available to the public information as follows . . .”);
Privacy Act, 5 U. S. C. §552a(d)(1) (“Each agency that maintains a
system of records shall . . . upon request by any individual to gain
access to his record or to any information pertaining to him which is
contained in the system, permit him and upon his request, a person of
his own choosing to accompany him, to review the record and have a
copy made of all or any portion thereof . . .”); Fair Credit Reporting Act,
15 U. S. C. §1681j(a)(1)(A) (“All consumer reporting agencies . . . shall
make all disclosures pursuant to section 1681g of this title once during
any 12-month period upon request of the consumer and without charge
to the consumer”); Right to Financial Privacy Act of 1978, 12 U. S. C.
§3404(c) (“The customer has the right . . . to obtain a copy of the record
which the financial institution shall keep of all instances in which the
customer’s record is disclosed to a Government authority pursuant to
this section, including the identity of the Government authority to
which such disclosure is made”); Government in the Sunshine Act, 5
U. S. C. §552b(f )(2) (“Copies of such transcript, or minutes, or a tran-
scription of such recording disclosing the identity of each speaker, shall
be furnished to any person at the actual cost of duplication or transcrip-
tion”); Cable Act, 47 U. S. C. §551(d) (“A cable subscriber shall be
provided access to all personally identifiable information regarding that
subscriber which is collected and maintained by a cable operator”);
Family Educational Rights and Privacy Act of 1974, 20 U. S. C.
§1232g(a)(1)(A) (“No funds shall be made available under any applica-
ble program to any educational agency or institution which has a policy
of denying, or which effectively prevents, the parents of students who
are or have been in attendance at a school of such agency or at such
institution, as the case may be, the right to inspect and review the
education records of their children. . . . Each educational agency or
institution shall establish appropriate procedures for the granting of a
request by parents for access to the education records of their children
within a reasonable period of time, but in no case more than forty-five
days after the request has been made”).
22 CARPENTER v. UNITED STATES
ALITO, J., dissenting
property.
Nor does the Telecommunications Act give Carpenter a
property right in the cell-site records simply because they
are subject to confidentiality restrictions. See 47 U. S. C.
§222(c)(1) (without a customer’s permission, a cell service
provider may generally “use, disclose, or permit access to
individually identifiable [cell-site records]” only with
respect to “its provision” of telecommunications services).
Many federal statutes impose similar restrictions on
private entities’ use or dissemination of information in
their own records without conferring a property right on
third parties.4
——————
4 See, e.g., Family Educational Rights and Privacy Act, 20 U. S. C.
§1232g(b)(1) (“No funds shall be made available under any applicable
program to any educational agency or institution which has a policy or
practice of permitting the release of education records (or personally
identifiable information contained therein other than directory infor-
mation . . . ) of students without the written consent of their parents to
any individual, agency, or organization . . .”); Video Privacy Protection
Act, 18 U. S. C. §2710(b)(1) (“A video tape service provider who know-
ingly discloses, to any person, personally identifiable information
concerning any consumer of such provider shall be liable to the ag-
grieved person for the relief provided in subsection (d)”); Driver Privacy
Protection Act, 18 U. S. C. §2721(a)(1) (“A State department of motor
vehicles, and any officer, employee, or contractor thereof, shall not
knowingly disclose or otherwise make available to any person or entity
. . . personal information . . .”); Fair Credit Reporting Act, 15 U. S. C.
§1681b(a) (“[A]ny consumer reporting agency may furnish a consumer
report under the following circumstances and no other . . .”); Right to
Financial Privacy Act, 12 U. S. C. §3403(a) (“No financial institution, or
officer, employees, or agent of a financial institution, may provide to
any Government authority access to or copies of, or the information
contained in, the financial records of any customer except in accordance
with the provisions of this chapter”); Patient Safety and Quality Im-
provement Act, 42 U. S. C. §299b–22(b) (“Notwithstanding any other
provision of Federal, State, or local law, and subject to subsection (c) of
this section, patient safety work product shall be confidential and shall
not be disclosed”); Cable Act, 47 U. S. C. §551(c)(1) (“[A] cable operator
shall not disclose personally identifiable information concerning any
subscriber without the prior written or electronic consent of the sub-
Cite as: 585 U. S. ____ (2018) 23
ALITO, J., dissenting
It would be especially strange to hold that the Telecom-
munication Act’s confidentiality provision confers a prop-
erty right when the Act creates an express exception for
any disclosure of records that is “required by law.” 47
U. S. C. §222(c)(1). So not only does Carpenter lack “ ‘the
most essential and beneficial’ ” of the “ ‘constituent ele-
ments’ ” of property, Dickman v. Commissioner, 465 U. S.
330, 336 (1984)—i.e., the right to use the property to the
exclusion of others—but he cannot even exclude the party
he would most like to keep out, namely, the Government.5
For all these reasons, there is no plausible ground for
maintaining that the information at issue here represents
Carpenter’s “papers” or “effects.”6
——————
scriber concerned and shall take such actions as are necessary to
prevent unauthorized access to such information by a person other than
the subscriber or cable operator”).
5 Carpenter also cannot argue that he owns the cell-site records merely
because they fall into the category of records referred to as “customer
proprietary network information.” 47 U. S. C. §222(c). Even assuming
labels alone can confer property rights, nothing in this particular label
indicates whether the “information” is “proprietary” to the “customer”
or to the provider of the “network.” At best, the phrase “customer
proprietary network information” is ambiguous, and context makes
clear that it refers to the provider’s information. The Telecommunica-
tions Act defines the term to include all “information that relates to the
quantity, technical configuration, type, destination, location, and
amount of use of a telecommunications service subscribed to by any
customer of a telecommunications carrier, and that is made available to
the carrier by the customer solely by virtue of the carrier-customer
relationship.” 47 U. S. C. §222(h)(1)(A). For Carpenter to be right, he
must own not only the cell-site records in this case, but also records
relating to, for example, the “technical configuration” of his subscribed
service—records that presumably include such intensely personal and
private information as transmission wavelengths, transport protocols,
and link layer system configurations.
6 Thus, this is not a case in which someone has entrusted papers that
he or she owns to the safekeeping of another, and it does not involve a
bailment. Cf. post, at 14 (GORSUCH, J., dissenting).
24 CARPENTER v. UNITED STATES
ALITO, J., dissenting
B
In the days when this Court followed an exclusively
property-based approach to the Fourth Amendment, the
distinction between an individual’s Fourth Amendment
rights and those of a third party was clear cut. We first
asked whether the object of the search—say, a house,
papers, or effects—belonged to the defendant, and, if it
did, whether the Government had committed a “trespass”
in acquiring the evidence at issue. Jones, 565 U. S., at
411, n. 8.
When the Court held in Katz that “property rights are
not the sole measure of Fourth Amendment violations,”
Soldal v. Cook County, 506 U. S. 56, 64 (1992), the sharp
boundary between personal and third-party rights was
tested. Under Katz, a party may invoke the Fourth
Amendment whenever law enforcement officers violate the
party’s “justifiable” or “reasonable” expectation of privacy.
See 389 U. S., at 353; see also id., at 361 (Harlan, J.,
concurring) (applying the Fourth Amendment where “a
person [has] exhibited an actual (subjective) expectation of
privacy” and where that “expectation [is] one that society
is prepared to recognize as ‘reasonable’ ”). Thus freed from
the limitations imposed by property law, parties began to
argue that they had a reasonable expectation of privacy in
items owned by others. After all, if a trusted third party
took care not to disclose information about the person in
question, that person might well have a reasonable expec-
tation that the information would not be revealed.
Efforts to claim Fourth Amendment protection against
searches of the papers and effects of others came to a head
in Miller, 425 U. S. 435, where the defendant sought the
suppression of two banks’ microfilm copies of his checks,
deposit slips, and other records. The defendant did not
claim that he owned these documents, but he nonetheless
argued that “analysis of ownership, property rights and
possessory interests in the determination of Fourth
Cite as: 585 U. S. ____ (2018) 25
ALITO, J., dissenting
Amendment rights ha[d] been severely impeached” by
Katz and other recent cases. See Brief for Respondent in
United States v. Miller, O. T. 1975, No. 74–1179, p. 6.
Turning to Katz, he then argued that he had a reasonable
expectation of privacy in the banks’ records regarding his
accounts. Brief for Respondent in No. 74–1179, at 6; see
also Miller, supra, at 442–443.
Acceptance of this argument would have flown in the
face of the Fourth Amendment’s text, and the Court re-
jected that development. Because Miller gave up “domin-
ion and control” of the relevant information to his bank,
Rakas, 439 U. S., at 149, the Court ruled that he lost any
protected Fourth Amendment interest in that information.
See Miller, supra, at 442–443. Later, in Smith v. Mary-
land, 442 U. S. 735, 745 (1979), the Court reached a simi-
lar conclusion regarding a telephone company’s records of
a customer’s calls. As JUSTICE KENNEDY concludes, Miller
and Smith are thus best understood as placing “necessary
limits on the ability of individuals to assert Fourth
Amendment interests in property to which they lack a
‘requisite connection.’ ” Ante, at 8.
The same is true here, where Carpenter indisputably
lacks any meaningful property-based connection to the
cell-site records owned by his provider. Because the rec-
ords are not Carpenter’s in any sense, Carpenter may not
seek to use the Fourth Amendment to exclude them.
By holding otherwise, the Court effectively allows Car-
penter to object to the “search” of a third party’s property,
not recognizing the revolutionary nature of this change.
The Court seems to think that Miller and Smith invented
a new “doctrine”—“the third-party doctrine”—and the
Court refuses to “extend” this product of the 1970’s to a
new age of digital communications. Ante, at 11, 17. But
the Court fundamentally misunderstands the role of Mil-
ler and Smith. Those decisions did not forge a new doc-
trine; instead, they rejected an argument that would have
26 CARPENTER v. UNITED STATES
ALITO, J., dissenting
disregarded the clear text of the Fourth Amendment and a
formidable body of precedent.
In the end, the Court never explains how its decision
can be squared with the fact that the Fourth Amendment
protects only “[t]he right of the people to be secure in their
persons, houses, papers, and effects.” (Emphasis added.)
* * *
Although the majority professes a desire not to “ ‘embar-
rass the future,’ ” ante, at 18, we can guess where today’s
decision will lead.
One possibility is that the broad principles that the
Court seems to embrace will be applied across the board.
All subpoenas duces tecum and all other orders compelling
the production of documents will require a demonstration
of probable cause, and individuals will be able to claim a
protected Fourth Amendment interest in any sensitive
personal information about them that is collected and
owned by third parties. Those would be revolutionary
developments indeed.
The other possibility is that this Court will face the
embarrassment of explaining in case after case that the
principles on which today’s decision rests are subject to all
sorts of qualifications and limitations that have not yet
been discovered. If we take this latter course, we will
inevitably end up “mak[ing] a crazy quilt of the Fourth
Amendment.” Smith, supra, at 745.
All of this is unnecessary. In the Stored Communica-
tions Act, Congress addressed the specific problem at issue
in this case. The Act restricts the misuse of cell-site rec-
ords by cell service providers, something that the Fourth
Amendment cannot do. The Act also goes beyond current
Fourth Amendment case law in restricting access by law
enforcement. It permits law enforcement officers to ac-
quire cell-site records only if they meet a heightened
standard and obtain a court order. If the American people
Cite as: 585 U. S. ____ (2018) 27
ALITO, J., dissenting
now think that the Act is inadequate or needs updating,
they can turn to their elected representatives to adopt
more protective provisions. Because the collection and
storage of cell-site records affects nearly every American,
it is unlikely that the question whether the current law
requires strengthening will escape Congress’s notice.
Legislation is much preferable to the development of an
entirely new body of Fourth Amendment caselaw for many
reasons, including the enormous complexity of the subject,
the need to respond to rapidly changing technology, and
the Fourth Amendment’s limited scope. The Fourth
Amendment restricts the conduct of the Federal Govern-
ment and the States; it does not apply to private actors.
But today, some of the greatest threats to individual pri-
vacy may come from powerful private companies that
collect and sometimes misuse vast quantities of data about
the lives of ordinary Americans. If today’s decision en-
courages the public to think that this Court can protect
them from this looming threat to their privacy, the deci-
sion will mislead as well as disrupt. And if holding a
provision of the Stored Communications Act to be uncon-
stitutional dissuades Congress from further legislation in
this field, the goal of protecting privacy will be greatly
disserved.
The desire to make a statement about privacy in the
digital age does not justify the consequences that today’s
decision is likely to produce.
Cite as: 585 U. S. ____ (2018) 1
GORSUCH, J., dissenting
SUPREME COURT OF THE UNITED STATES
_________________
No. 16–402
_________________
TIMOTHY IVORY CARPENTER, PETITIONER v.
UNITED STATES
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE SIXTH CIRCUIT
[June 22, 2018]
JUSTICE GORSUCH, dissenting.
In the late 1960s this Court suggested for the first time
that a search triggering the Fourth Amendment occurs
when the government violates an “expectation of privacy”
that “society is prepared to recognize as ‘reasonable.’ ”
Katz v. United States, 389 U. S. 347, 361 (1967) (Harlan,
J., concurring). Then, in a pair of decisions in the 1970s
applying the Katz test, the Court held that a “reasonable
expectation of privacy” doesn’t attach to information
shared with “third parties.” See Smith v. Maryland, 442
U. S. 735, 743–744 (1979); United States v. Miller, 425
U. S. 435, 443 (1976). By these steps, the Court came to
conclude, the Constitution does nothing to limit investiga-
tors from searching records you’ve entrusted to your bank,
accountant, and maybe even your doctor.
What’s left of the Fourth Amendment? Today we use
the Internet to do most everything. Smartphones make it
easy to keep a calendar, correspond with friends, make
calls, conduct banking, and even watch the game. Count-
less Internet companies maintain records about us and,
increasingly, for us. Even our most private documents—
those that, in other eras, we would have locked safely in a
desk drawer or destroyed—now reside on third party
servers. Smith and Miller teach that the police can review
all of this material, on the theory that no one reasonably
2 CARPENTER v. UNITED STATES
GORSUCH, J., dissenting
expects any of it will be kept private. But no one believes
that, if they ever did.
What to do? It seems to me we could respond in at least
three ways. The first is to ignore the problem, maintain
Smith and Miller, and live with the consequences. If the
confluence of these decisions and modern technology
means our Fourth Amendment rights are reduced to nearly
nothing, so be it. The second choice is to set Smith and
Miller aside and try again using the Katz “reasonable
expectation of privacy” jurisprudence that produced them.
The third is to look for answers elsewhere.
*
Start with the first option. Smith held that the govern-
ment’s use of a pen register to record the numbers people
dial on their phones doesn’t infringe a reasonable expecta-
tion of privacy because that information is freely disclosed
to the third party phone company. 442 U. S., at 743–744.
Miller held that a bank account holder enjoys no reason-
able expectation of privacy in the bank’s records of his
account activity. That’s true, the Court reasoned, “even if
the information is revealed on the assumption that it will
be used only for a limited purpose and the confidence
placed in the third party will not be betrayed.” 425 U. S.,
at 443. Today the Court suggests that Smith and Miller
distinguish between kinds of information disclosed to third
parties and require courts to decide whether to “extend”
those decisions to particular classes of information, de-
pending on their sensitivity. See ante, at 10–18. But as
the Sixth Circuit recognized and JUSTICE KENNEDY ex-
plains, no balancing test of this kind can be found in
Smith and Miller. See ante, at 16 (dissenting opinion).
Those cases announced a categorical rule: Once you dis-
close information to third parties, you forfeit any reason-
able expectation of privacy you might have had in it. And
even if Smith and Miller did permit courts to conduct a
Cite as: 585 U. S. ____ (2018) 3
GORSUCH, J., dissenting
balancing contest of the kind the Court now suggests, it’s
still hard to see how that would help the petitioner in this
case. Why is someone’s location when using a phone so
much more sensitive than who he was talking to (Smith)
or what financial transactions he engaged in (Miller)? I do
not know and the Court does not say.
The problem isn’t with the Sixth Circuit’s application of
Smith and Miller but with the cases themselves. Can the
government demand a copy of all your e-mails from Google
or Microsoft without implicating your Fourth Amendment
rights? Can it secure your DNA from 23andMe without a
warrant or probable cause? Smith and Miller say yes it
can—at least without running afoul of Katz. But that
result strikes most lawyers and judges today—me in-
cluded—as pretty unlikely. In the years since its adoption,
countless scholars, too, have come to conclude that the
“third-party doctrine is not only wrong, but horribly
wrong.” Kerr, The Case for the Third-Party Doctrine, 107
Mich. L. Rev. 561, 563, n. 5, 564 (2009) (collecting criti-
cisms but defending the doctrine (footnotes omitted)). The
reasons are obvious. “As an empirical statement about
subjective expectations of privacy,” the doctrine is “quite
dubious.” Baude & Stern, The Positive Law Model of the
Fourth Amendment, 129 Harv. L. Rev. 1821, 1872 (2016).
People often do reasonably expect that information they
entrust to third parties, especially information subject to
confidentiality agreements, will be kept private. Mean-
while, if the third party doctrine is supposed to represent
a normative assessment of when a person should expect
privacy, the notion that the answer might be “never”
seems a pretty unattractive societal prescription. Ibid.
What, then, is the explanation for our third party doc-
trine? The truth is, the Court has never offered a persua-
sive justification. The Court has said that by conveying
information to a third party you “ ‘assum[e] the risk’ ” it
will be revealed to the police and therefore lack a reason-
4 CARPENTER v. UNITED STATES
GORSUCH, J., dissenting
able expectation of privacy in it. Smith, supra, at 744. But
assumption of risk doctrine developed in tort law. It
generally applies when “by contract or otherwise [one]
expressly agrees to accept a risk of harm” or impliedly
does so by “manifest[ing] his willingness to accept” that
risk and thereby “take[s] his chances as to harm which
may result from it.” Restatement (Second) of Torts
§§496B, 496C(1), and Comment b (1965); see also 1 D.
Dobbs, P. Hayden, & E. Bublick, Law of Torts §§235–236,
pp. 841–850 (2d ed. 2017). That rationale has little play in
this context. Suppose I entrust a friend with a letter and
he promises to keep it secret until he delivers it to an
intended recipient. In what sense have I agreed to bear
the risk that he will turn around, break his promise, and
spill its contents to someone else? More confusing still,
what have I done to “manifest my willingness to accept”
the risk that the government will pry the document from
my friend and read it without his consent?
One possible answer concerns knowledge. I know that
my friend might break his promise, or that the govern-
ment might have some reason to search the papers in his
possession. But knowing about a risk doesn’t mean you
assume responsibility for it. Whenever you walk down the
sidewalk you know a car may negligently or recklessly
veer off and hit you, but that hardly means you accept the
consequences and absolve the driver of any damage he
may do to you. Epstein, Privacy and the Third Hand:
Lessons From the Common Law of Reasonable Expecta-
tions, 24 Berkeley Tech. L. J. 1199, 1204 (2009); see W.
Keeton, D. Dobbs, R. Keeton, & D. Owen, Prosser & Keeton
on Law of Torts 490 (5th ed. 1984).
Some have suggested the third party doctrine is better
understood to rest on consent than assumption of risk.
“So long as a person knows that they are disclosing infor-
mation to a third party,” the argument goes, “their choice
to do so is voluntary and the consent valid.” Kerr, supra,
Cite as: 585 U. S. ____ (2018) 5
GORSUCH, J., dissenting
at 588. I confess I still don’t see it. Consenting to give a
third party access to private papers that remain my prop-
erty is not the same thing as consenting to a search of
those papers by the government. Perhaps there are excep-
tions, like when the third party is an undercover govern-
ment agent. See Murphy, The Case Against the Case
Against the Third-Party Doctrine: A Response to Epstein
and Kerr, 24 Berkeley Tech. L. J. 1239, 1252 (2009); cf.
Hoffa v. United States, 385 U. S. 293 (1966). But other-
wise this conception of consent appears to be just assump-
tion of risk relabeled—you’ve “consented” to whatever
risks are foreseeable.
Another justification sometimes offered for third party
doctrine is clarity. You (and the police) know exactly how
much protection you have in information confided to oth-
ers: none. As rules go, “the king always wins” is admi-
rably clear. But the opposite rule would be clear too: Third
party disclosures never diminish Fourth Amendment
protection (call it “the king always loses”). So clarity alone
cannot justify the third party doctrine.
In the end, what do Smith and Miller add up to? A
doubtful application of Katz that lets the government
search almost whatever it wants whenever it wants. The
Sixth Circuit had to follow that rule and faithfully did just
that, but it’s not clear why we should.
*
There’s a second option. What if we dropped Smith and
Miller’s third party doctrine and retreated to the root Katz
question whether there is a “reasonable expectation of
privacy” in data held by third parties? Rather than solve
the problem with the third party doctrine, I worry this
option only risks returning us to its source: After all, it
was Katz that produced Smith and Miller in the first
place.
Katz’s problems start with the text and original under-
6 CARPENTER v. UNITED STATES
GORSUCH, J., dissenting
standing of the Fourth Amendment, as JUSTICE THOMAS
thoughtfully explains today. Ante, at 5–17 (dissenting
opinion). The Amendment’s protections do not depend on
the breach of some abstract “expectation of privacy” whose
contours are left to the judicial imagination. Much more
concretely, it protects your “person,” and your “houses,
papers, and effects.” Nor does your right to bring a Fourth
Amendment claim depend on whether a judge happens to
agree that your subjective expectation to privacy is a
“reasonable” one. Under its plain terms, the Amendment
grants you the right to invoke its guarantees whenever
one of your protected things (your person, your house, your
papers, or your effects) is unreasonably searched or seized.
Period.
History too holds problems for Katz. Little like it can be
found in the law that led to the adoption of the Fourth
Amendment or in this Court’s jurisprudence until the late
1960s. The Fourth Amendment came about in response to
a trio of 18th century cases “well known to the men who
wrote and ratified the Bill of Rights, [and] famous
throughout the colonial population.” Stuntz, The Substan-
tive Origins of Criminal Procedure, 105 Yale L. J. 393, 397
(1995). The first two were English cases invalidating the
Crown’s use of general warrants to enter homes and
search papers. Entick v. Carrington, 19 How. St. Tr. 1029
(K. B. 1765); Wilkes v. Wood, 19 How. St. Tr. 1153 (K. B.
1763); see W. Cuddihy, The Fourth Amendment: Origins
and Original Meaning 439–487 (2009); Boyd v. United
States, 116 U. S. 616, 625–630 (1886). The third was
American: the Boston Writs of Assistance Case, which
sparked colonial outrage at the use of writs permitting
government agents to enter houses and business, breaking
open doors and chests along the way, to conduct searches
and seizures—and to force third parties to help them.
Stuntz, supra, at 404–409; M. Smith, The Writs of Assis-
tance Case (1978). No doubt the colonial outrage engen-
Cite as: 585 U. S. ____ (2018) 7
GORSUCH, J., dissenting
dered by these cases rested in part on the government’s
intrusion upon privacy. But the framers chose not to
protect privacy in some ethereal way dependent on judicial
intuitions. They chose instead to protect privacy in par-
ticular places and things—“persons, houses, papers, and
effects”—and against particular threats—“unreasonable”
governmental “searches and seizures.” See Entick, supra,
at 1066 (“Papers are the owner’s goods and chattels; they
are his dearest property; and so far from enduring a sei-
zure, that they will hardly bear an inspection”); see also
ante, at 1–21 (THOMAS, J., dissenting).
Even taken on its own terms, Katz has never been suffi-
ciently justified. In fact, we still don’t even know what its
“reasonable expectation of privacy” test is. Is it supposed
to pose an empirical question (what privacy expectations
do people actually have) or a normative one (what expecta-
tions should they have)? Either way brings problems. If
the test is supposed to be an empirical one, it’s unclear
why judges rather than legislators should conduct it.
Legislators are responsive to their constituents and have
institutional resources designed to help them discern and
enact majoritarian preferences. Politically insulated
judges come armed with only the attorneys’ briefs, a few
law clerks, and their own idiosyncratic experiences. They
are hardly the representative group you’d expect (or want)
to be making empirical judgments for hundreds of millions
of people. Unsurprisingly, too, judicial judgments often
fail to reflect public views. See Slobogin & Schumacher,
Reasonable Expectations of Privacy and Autonomy in
Fourth Amendment Cases: An Empirical Look at “Under-
standings Recognized and Permitted by Society,” 42 Duke
L. J. 727, 732, 740–742 (1993). Consider just one example.
Our cases insist that the seriousness of the offense being
investigated does not reduce Fourth Amendment protec-
tion. Mincey v. Arizona, 437 U. S. 385, 393–394 (1978).
Yet scholars suggest that most people are more tolerant of
8 CARPENTER v. UNITED STATES
GORSUCH, J., dissenting
police intrusions when they investigate more serious
crimes. See Blumenthal, Adya, & Mogle, The Multiple
Dimensions of Privacy: Testing Lay “Expectations of Pri-
vacy,” 11 U. Pa. J. Const. L. 331, 352–353 (2009). And I
very much doubt that this Court would be willing to adjust
its Katz cases to reflect these findings even if it believed
them.
Maybe, then, the Katz test should be conceived as a
normative question. But if that’s the case, why (again) do
judges, rather than legislators, get to determine whether
society should be prepared to recognize an expectation of
privacy as legitimate? Deciding what privacy interests
should be recognized often calls for a pure policy choice,
many times between incommensurable goods—between
the value of privacy in a particular setting and society’s
interest in combating crime. Answering questions like
that calls for the exercise of raw political will belonging to
legislatures, not the legal judgment proper to courts. See
The Federalist No. 78, p. 465 (C. Rossiter ed. 1961) (A.
Hamilton). When judges abandon legal judgment for
political will we not only risk decisions where “reasonable
expectations of privacy” come to bear “an uncanny resem-
blance to those expectations of privacy” shared by Mem-
bers of this Court. Minnesota v. Carter, 525 U. S. 83, 97
(1998) (Scalia, J., concurring). We also risk undermining
public confidence in the courts themselves.
My concerns about Katz come with a caveat. Sometimes,
I accept, judges may be able to discern and describe exist-
ing societal norms. See, e.g., Florida v. Jardines, 569 U. S.
1, 8 (2013) (inferring a license to enter on private property
from the “ ‘habits of the country’ ” (quoting McKee v. Gratz,
260 U. S. 127, 136 (1922))); Sachs, Finding Law, 107 Cal.
L. Rev. (forthcoming 2019), online at https://ssrn.com/
abstract=3064443 (as last visited June 19, 2018). That is
particularly true when the judge looks to positive law
rather than intuition for guidance on social norms. See
Cite as: 585 U. S. ____ (2018) 9
GORSUCH, J., dissenting
Byrd v. United States, 584 U. S. ___, ___–___ (2018) (slip
op., at 7–9) (“general property-based concept[s] guid[e] the
resolution of this case”). So there may be some occasions
where Katz is capable of principled application—though it
may simply wind up approximating the more traditional
option I will discuss in a moment. Sometimes it may also
be possible to apply Katz by analogizing from precedent
when the line between an existing case and a new fact
pattern is short and direct. But so far this Court has
declined to tie itself to any significant restraints like
these. See ante, at 5, n. 1 (“[W]hile property rights are
often informative, our cases by no means suggest that
such an interest is ‘fundamental’ or ‘dispositive’ in deter-
mining which expectations of privacy are legitimate”).
As a result, Katz has yielded an often unpredictable—
and sometimes unbelievable—jurisprudence. Smith and
Miller are only two examples; there are many others.
Take Florida v. Riley, 488 U. S. 445 (1989), which says
that a police helicopter hovering 400 feet above a person’s
property invades no reasonable expectation of privacy.
Try that one out on your neighbors. Or California v.
Greenwood, 486 U. S. 35 (1988), which holds that a person
has no reasonable expectation of privacy in the garbage he
puts out for collection. In that case, the Court said that
the homeowners forfeited their privacy interests because
“[i]t is common knowledge that plastic garbage bags left on
or at the side of a public street are readily accessible to
animals, children, scavengers, snoops, and other members
of the public.” Id., at 40 (footnotes omitted). But the
habits of raccoons don’t prove much about the habits of the
country. I doubt, too, that most people spotting a neighbor
rummaging through their garbage would think they
lacked reasonable grounds to confront the rummager.
Making the decision all the stranger, California state law
expressly protected a homeowner’s property rights in
discarded trash. Id., at 43. Yet rather than defer to that
10 CARPENTER v. UNITED STATES
GORSUCH, J., dissenting
as evidence of the people’s habits and reasonable expecta-
tions of privacy, the Court substituted its own curious
judgment.
Resorting to Katz in data privacy cases threatens more
of the same. Just consider. The Court today says that
judges should use Katz’s reasonable expectation of privacy
test to decide what Fourth Amendment rights people have
in cell-site location information, explaining that “no single
rubric definitively resolves which expectations of privacy
are entitled to protection.” Ante, at 5. But then it offers a
twist. Lower courts should be sure to add two special
principles to their Katz calculus: the need to avoid “arbi-
trary power” and the importance of “plac[ing] obstacles in
the way of a too permeating police surveillance.” Ante, at
6 (internal quotation marks omitted). While surely lauda-
ble, these principles don’t offer lower courts much guid-
ance. The Court does not tell us, for example, how far to
carry either principle or how to weigh them against the
legitimate needs of law enforcement. At what point does
access to electronic data amount to “arbitrary” authority?
When does police surveillance become “too permeating”?
And what sort of “obstacles” should judges “place” in law
enforcement’s path when it does? We simply do not know.
The Court’s application of these principles supplies little
more direction. The Court declines to say whether there is
any sufficiently limited period of time “for which the Gov-
ernment may obtain an individual’s historical [location
information] free from Fourth Amendment scrutiny.”
Ante, at 11, n. 3; see ante, at 11–15. But then it tells us
that access to seven days’ worth of information does trig-
ger Fourth Amendment scrutiny—even though here the
carrier “produced only two days of records.” Ante, at 11, n.
3. Why is the relevant fact the seven days of information
the government asked for instead of the two days of infor-
mation the government actually saw? Why seven days
instead of ten or three or one? And in what possible sense
Cite as: 585 U. S. ____ (2018) 11
GORSUCH, J., dissenting
did the government “search” five days’ worth of location
information it was never even sent? We do not know.
Later still, the Court adds that it can’t say whether the
Fourth Amendment is triggered when the government
collects “real-time CSLI or ‘tower dumps’ (a download of
information on all the devices that connected to a particu-
lar cell site during a particular interval).” Ante, at 17–18.
But what distinguishes historical data from real-time
data, or seven days of a single person’s data from a down-
load of everyone’s data over some indefinite period of time?
Why isn’t a tower dump the paradigmatic example of “too
permeating police surveillance” and a dangerous tool of
“arbitrary” authority—the touchstones of the majority’s
modified Katz analysis? On what possible basis could such
mass data collection survive the Court’s test while collect-
ing a single person’s data does not? Here again we are left
to guess. At the same time, though, the Court offers some
firm assurances. It tells us its decision does not “call into
question conventional surveillance techniques and tools,
such as security cameras.” Ibid. That, however, just
raises more questions for lower courts to sort out about
what techniques qualify as “conventional” and why those
techniques would be okay even if they lead to “permeating
police surveillance” or “arbitrary police power.”
Nor is this the end of it. After finding a reasonable
expectation of privacy, the Court says there’s still more
work to do. Courts must determine whether to “extend”
Smith and Miller to the circumstances before them. Ante,
at 11, 15–17. So apparently Smith and Miller aren’t quite
left for dead; they just no longer have the clear reach they
once did. How do we measure their new reach? The Court
says courts now must conduct a second Katz-like balancing
inquiry, asking whether the fact of disclosure to a third
party outweighs privacy interests in the “category of in-
formation” so disclosed. Ante, at 13, 15–16. But how are
lower courts supposed to weigh these radically different
12 CARPENTER v. UNITED STATES
GORSUCH, J., dissenting
interests? Or assign values to different categories of
information? All we know is that historical cell-site loca-
tion information (for seven days, anyway) escapes Smith
and Miller’s shorn grasp, while a lifetime of bank or phone
records does not. As to any other kind of information,
lower courts will have to stay tuned.
In the end, our lower court colleagues are left with two
amorphous balancing tests, a series of weighty and in-
commensurable principles to consider in them, and a few
illustrative examples that seem little more than the prod-
uct of judicial intuition. In the Court’s defense, though,
we have arrived at this strange place not because the
Court has misunderstood Katz. Far from it. We have
arrived here because this is where Katz inevitably leads.
*
There is another way. From the founding until the
1960s, the right to assert a Fourth Amendment claim
didn’t depend on your ability to appeal to a judge’s per-
sonal sensibilities about the “reasonableness” of your expecta-
tions or privacy. It was tied to the law. Jardines, 569
U. S., at 11; United States v. Jones, 565 U. S. 400, 405
(2012). The Fourth Amendment protects “the right of the
people to be secure in their persons, houses, papers and
effects, against unreasonable searches and seizures.” True
to those words and their original understanding, the tradi-
tional approach asked if a house, paper or effect was yours
under law. No more was needed to trigger the Fourth
Amendment. Though now often lost in Katz’s shadow, this
traditional understanding persists. Katz only “supple-
ments, rather than displaces the traditional property-
based understanding of the Fourth Amendment.” Byrd,
584 U. S., at ___ (slip op., at 7) (internal quotation marks
omitted); Jardines, supra, at 11 (same); Soldal v. Cook
County, 506 U. S. 56, 64 (1992) (Katz did not “snuf[f ] out
the previously recognized protection for property under
Cite as: 585 U. S. ____ (2018) 13
GORSUCH, J., dissenting
the Fourth Amendment”).
Beyond its provenance in the text and original under-
standing of the Amendment, this traditional approach
comes with other advantages. Judges are supposed to
decide cases based on “democratically legitimate sources of
law”—like positive law or analogies to items protected by
the enacted Constitution—rather than “their own biases
or personal policy preferences.” Pettys, Judicial Discretion
in Constitutional Cases, 26 J. L. & Pol. 123, 127 (2011). A
Fourth Amendment model based on positive legal rights
“carves out significant room for legislative participation in
the Fourth Amendment context,” too, by asking judges to
consult what the people’s representatives have to say
about their rights. Baude & Stern, 129 Harv. L. Rev., at
1852. Nor is this approach hobbled by Smith and Miller,
for those cases are just limitations on Katz, addressing
only the question whether individuals have a reasonable
expectation of privacy in materials they share with third
parties. Under this more traditional approach, Fourth
Amendment protections for your papers and effects do not
automatically disappear just because you share them with
third parties.
Given the prominence Katz has claimed in our doctrine,
American courts are pretty rusty at applying the tradi-
tional approach to the Fourth Amendment. We know that
if a house, paper, or effect is yours, you have a Fourth
Amendment interest in its protection. But what kind of
legal interest is sufficient to make something yours? And
what source of law determines that? Current positive
law? The common law at 1791, extended by analogy to
modern times? Both? See Byrd, supra, at ___–___ (slip
op., at 1–2) (THOMAS, J., concurring); cf. Re, The Positive
Law Floor, 129 Harv. L. Rev. Forum 313 (2016). Much
work is needed to revitalize this area and answer these
questions. I do not begin to claim all the answers today,
but (unlike with Katz) at least I have a pretty good idea
14 CARPENTER v. UNITED STATES
GORSUCH, J., dissenting
what the questions are. And it seems to me a few things
can be said.
First, the fact that a third party has access to or posses-
sion of your papers and effects does not necessarily elimi-
nate your interest in them. Ever hand a private document
to a friend to be returned? Toss your keys to a valet at a
restaurant? Ask your neighbor to look after your dog
while you travel? You would not expect the friend to share
the document with others; the valet to lend your car to his
buddy; or the neighbor to put Fido up for adoption. En-
trusting your stuff to others is a bailment. A bailment is
the “delivery of personal property by one person (the bailor)
to another (the bailee) who holds the property for a
certain purpose.” Black’s Law Dictionary 169 (10th ed.
2014); J. Story, Commentaries on the Law of Bailments
§2, p. 2 (1832) (“a bailment is a delivery of a thing in trust
for some special object or purpose, and upon a contract,
expressed or implied, to conform to the object or purpose of
the trust”). A bailee normally owes a legal duty to keep
the item safe, according to the terms of the parties’ con-
tract if they have one, and according to the “implication[s]
from their conduct” if they don’t. 8 C. J. S., Bailments §36,
pp. 468–469 (2017). A bailee who uses the item in a dif-
ferent way than he’s supposed to, or against the bailor’s
instructions, is liable for conversion. Id., §43, at 481; see
Goad v. Harris, 207 Ala. 357, 92 So. 546, (1922); Knight v.
Seney, 290 Ill. 11, 17, 124 N. E. 813, 815–816 (1919);
Baxter v. Woodward, 191 Mich. 379, 385, 158 N. W. 137,
139 (1916). This approach is quite different from Smith
and Miller’s (counter)-intuitive approach to reasonable
expectations of privacy; where those cases extinguish
Fourth Amendment interests once records are given to a
third party, property law may preserve them.
Our Fourth Amendment jurisprudence already reflects
this truth. In Ex parte Jackson, 96 U. S. 727 (1878), this
Court held that sealed letters placed in the mail are “as
Cite as: 585 U. S. ____ (2018) 15
GORSUCH, J., dissenting
fully guarded from examination and inspection, except as
to their outward form and weight, as if they were retained
by the parties forwarding them in their own domiciles.”
Id., at 733. The reason, drawn from the Fourth Amend-
ment’s text, was that “[t]he constitutional guaranty of the
right of the people to be secure in their papers against
unreasonable searches and seizures extends to their pa-
pers, thus closed against inspection, wherever they may
be.” Ibid. (emphasis added). It did not matter that letters
were bailed to a third party (the government, no less).
The sender enjoyed the same Fourth Amendment protec-
tion as he does “when papers are subjected to search in
one’s own household.” Ibid.
These ancient principles may help us address modern
data cases too. Just because you entrust your data—in
some cases, your modern-day papers and effects—to a
third party may not mean you lose any Fourth Amend-
ment interest in its contents. Whatever may be left of
Smith and Miller, few doubt that e-mail should be treated
much like the traditional mail it has largely supplanted—
as a bailment in which the owner retains a vital and pro-
tected legal interest. See ante, at 13 (KENNEDY, J., dis-
senting) (noting that enhanced Fourth Amendment protec-
tion may apply when the “modern-day equivalents of an
individual’s own ‘papers’ or ‘effects’ . . . are held by a third
party” through “bailment”); ante, at 23, n. 6 (ALITO, J.,
dissenting) (reserving the question whether Fourth
Amendment protection may apply in the case of “bail-
ment” or when “someone has entrusted papers he or she
owns . . . to the safekeeping of another”); United States v.
Warshak, 631 F. 3d 266, 285–286 (CA6 2010) (relying on
an analogy to Jackson to extend Fourth Amendment
protection to e-mail held by a third party service provider).
Second, I doubt that complete ownership or exclusive
control of property is always a necessary condition to the
assertion of a Fourth Amendment right. Where houses
16 CARPENTER v. UNITED STATES
GORSUCH, J., dissenting
are concerned, for example, individuals can enjoy Fourth
Amendment protection without fee simple title. Both the
text of the Amendment and the common law rule support
that conclusion. “People call a house ‘their’ home when
legal title is in the bank, when they rent it, and even when
they merely occupy it rent free.” Carter, 525 U. S., at 95–
96 (Scalia, J., concurring). That rule derives from the
common law. Oystead v. Shed, 13 Mass. 520, 523 (1816)
(explaining, citing “[t]he very learned judges, Foster, Hale,
and Coke,” that the law “would be as much disturbed by a
forcible entry to arrest a boarder or a servant, who had
acquired, by contract, express or implied, a right to enter
the house at all times, and to remain in it as long as they
please, as if the object were to arrest the master of the
house or his children”). That is why tenants and resident
family members—though they have no legal title—have
standing to complain about searches of the houses in
which they live. Chapman v. United States, 365 U. S. 610,
616–617 (1961), Bumper v. North Carolina, 391 U. S. 543,
548, n. 11 (1968).
Another point seems equally true: just because you have
to entrust a third party with your data doesn’t necessarily
mean you should lose all Fourth Amendment protections
in it. Not infrequently one person comes into possession of
someone else’s property without the owner’s consent.
Think of the finder of lost goods or the policeman who
impounds a car. The law recognizes that the goods and
the car still belong to their true owners, for “where a
person comes into lawful possession of the personal prop-
erty of another, even though there is no formal agreement
between the property’s owner and its possessor, the pos-
sessor will become a constructive bailee when justice so
requires.” Christensen v. Hoover, 643 P. 2d 525, 529 (Colo.
1982) (en banc); Laidlaw, Principles of Bailment, 16 Cor-
nell L. Q. 286 (1931). At least some of this Court’s deci-
sions have already suggested that use of technology is
Cite as: 585 U. S. ____ (2018) 17
GORSUCH, J., dissenting
functionally compelled by the demands of modern life, and
in that way the fact that we store data with third parties
may amount to a sort of involuntary bailment too. See
ante, at 12–13 (majority opinion); Riley v. California, 573
U. S. ___, ___ (2014) (slip op., at 9).
Third, positive law may help provide detailed guidance
on evolving technologies without resort to judicial intui-
tion. State (or sometimes federal) law often creates rights
in both tangible and intangible things. See Ruckelshaus v.
Monsanto Co., 467 U. S. 986, 1001 (1984). In the context
of the Takings Clause we often ask whether those state-
created rights are sufficient to make something someone’s
property for constitutional purposes. See id., at 1001–
1003; Louisville Joint Stock Land Bank v. Radford, 295
U. S. 555, 590–595 (1935). A similar inquiry may be
appropriate for the Fourth Amendment. Both the States
and federal government are actively legislating in the area
of third party data storage and the rights users enjoy.
See, e.g., Stored Communications Act, 18 U. S. C. §2701
et seq.; Tex. Prop. Code Ann. §111.004(12) (West 2017)
(defining “[p]roperty” to include “property held in any
digital or electronic medium”). State courts are busy
expounding common law property principles in this area
as well. E.g., Ajemian v. Yahoo!, Inc., 478 Mass. 169, 170,
84 N. E. 3d 766, 768 (2017) (e-mail account is a “form of
property often referred to as a ‘digital asset’ ”); Eysoldt v.
ProScan Imaging, 194 Ohio App. 3d 630, 638, 2011–Ohio–
2359, 957 N. E. 2d 780, 786 (2011) (permitting action for
conversion of web account as intangible property). If state
legislators or state courts say that a digital record has the
attributes that normally make something property, that
may supply a sounder basis for judicial decisionmaking
than judicial guesswork about societal expectations.
Fourth, while positive law may help establish a person’s
Fourth Amendment interest there may be some circum-
stances where positive law cannot be used to defeat it.
18 CARPENTER v. UNITED STATES
GORSUCH, J., dissenting
Ex parte Jackson reflects that understanding. There this
Court said that “[n]o law of Congress” could authorize
letter carriers “to invade the secrecy of letters.” 96 U. S.,
at 733. So the post office couldn’t impose a regulation
dictating that those mailing letters surrender all legal
interests in them once they’re deposited in a mailbox. If
that is right, Jackson suggests the existence of a constitu-
tional floor below which Fourth Amendment rights may
not descend. Legislatures cannot pass laws declaring your
house or papers to be your property except to the extent
the police wish to search them without cause. As the
Court has previously explained, “we must ‘assur[e] preser-
vation of that degree of privacy against government that
existed when the Fourth Amendment was adopted.’ ”
Jones, 565 U. S., at 406 (quoting Kyllo v. United States,
533 U. S. 27, 34 (2001)). Nor does this mean protecting
only the specific rights known at the founding; it means
protecting their modern analogues too. So, for example,
while thermal imaging was unknown in 1791, this Court
has recognized that using that technology to look inside a
home constitutes a Fourth Amendment “search” of that
“home” no less than a physical inspection might. Id.,
at 40.
Fifth, this constitutional floor may, in some instances,
bar efforts to circumvent the Fourth Amendment’s protec-
tion through the use of subpoenas. No one thinks the
government can evade Jackson’s prohibition on opening
sealed letters without a warrant simply by issuing a sub-
poena to a postmaster for “all letters sent by John Smith”
or, worse, “all letters sent by John Smith concerning a
particular transaction.” So the question courts will con-
front will be this: What other kinds of records are suffi-
ciently similar to letters in the mail that the same rule
should apply?
It may be that, as an original matter, a subpoena requir-
ing the recipient to produce records wasn’t thought of as a
Cite as: 585 U. S. ____ (2018) 19
GORSUCH, J., dissenting
“search or seizure” by the government implicating the
Fourth Amendment, see ante, at 2–12 (opinion of ALITO,
J.), but instead as an act of compelled self-incrimination
implicating the Fifth Amendment, see United States v.
Hubbell, 530 U. S. 27, 49–55 (2000) (THOMAS, J., dissent-
ing); Nagareda, Compulsion “To Be a Witness” and the
Resurrection of Boyd, 74 N. Y. U. L. Rev. 1575, 1619, and
n. 172 (1999). But the common law of searches and sei-
zures does not appear to have confronted a case where
private documents equivalent to a mailed letter were
entrusted to a bailee and then subpoenaed. As a result,
“[t]he common-law rule regarding subpoenas for docu-
ments held by third parties entrusted with information
from the target is . . . unknown and perhaps unknowable.”
Dripps, Perspectives on The Fourth Amendment Forty
Years Later: Toward the Realization of an Inclusive Regu-
latory Model, 100 Minn. L. Rev. 1885, 1922 (2016). Given
that (perhaps insoluble) uncertainty, I am content to
adhere to Jackson and its implications for now.
To be sure, we must be wary of returning to the doctrine
of Boyd v. United States, 116 U. S. 616. Boyd invoked the
Fourth Amendment to restrict the use of subpoenas even
for ordinary business records and, as JUSTICE ALITO notes,
eventually proved unworkable. See ante, at 13 (dissenting
opinion); 3 W. LaFave, J. Israel, N. King, & O. Kerr, Crim-
inal Procedure §8.7(a), pp. 185–187 (4th ed. 2015). But if
we were to overthrow Jackson too and deny Fourth
Amendment protection to any subpoenaed materials, we
would do well to reconsider the scope of the Fifth Amend-
ment while we’re at it. Our precedents treat the right
against self-incrimination as applicable only to testimony,
not the production of incriminating evidence. See Fisher
v. United States, 425 U. S. 391, 401 (1976). But there is
substantial evidence that the privilege against self-
incrimination was also originally understood to protect a
person from being forced to turn over potentially incrimi-
20 CARPENTER v. UNITED STATES
GORSUCH, J., dissenting
nating evidence. Nagareda, supra, at 1605–1623; Rex v.
Purnell, 96 Eng. Rep. 20 (K. B. 1748); Slobogin, Privacy at
Risk 145 (2007).
*
What does all this mean for the case before us? To start,
I cannot fault the Sixth Circuit for holding that Smith and
Miller extinguish any Katz-based Fourth Amendment
interest in third party cell-site data. That is the plain
effect of their categorical holdings. Nor can I fault the
Court today for its implicit but unmistakable conclusion
that the rationale of Smith and Miller is wrong; indeed, I
agree with that. The Sixth Circuit was powerless to say
so, but this Court can and should. At the same time, I do
not agree with the Court’s decision today to keep Smith
and Miller on life support and supplement them with a
new and multilayered inquiry that seems to be only Katz-
squared. Returning there, I worry, promises more trouble
than help. Instead, I would look to a more traditional
Fourth Amendment approach. Even if Katz may still
supply one way to prove a Fourth Amendment interest, it
has never been the only way. Neglecting more traditional
approaches may mean failing to vindicate the full protec-
tions of the Fourth Amendment.
Our case offers a cautionary example. It seems to me
entirely possible a person’s cell-site data could qualify as
his papers or effects under existing law. Yes, the tele-
phone carrier holds the information. But 47 U. S. C. §222
designates a customer’s cell-site location information as
“customer proprietary network information” (CPNI),
§222(h)(1)(A), and gives customers certain rights to control
use of and access to CPNI about themselves. The statute
generally forbids a carrier to “use, disclose, or permit
access to individually identifiable” CPNI without the
customer’s consent, except as needed to provide the cus-
tomer’s telecommunications services. §222(c)(1). It also
Cite as: 585 U. S. ____ (2018) 21
GORSUCH, J., dissenting
requires the carrier to disclose CPNI “upon affirmative
written request by the customer, to any person designated
by the customer.” §222(c)(2). Congress even afforded
customers a private cause of action for damages against
carriers who violate the Act’s terms. §207. Plainly, cus-
tomers have substantial legal interests in this infor-
mation, including at least some right to include, exclude,
and control its use. Those interests might even rise to the
level of a property right.
The problem is that we do not know anything more.
Before the district court and court of appeals, Mr. Carpen-
ter pursued only a Katz “reasonable expectations” argu-
ment. He did not invoke the law of property or any analo-
gies to the common law, either there or in his petition for
certiorari. Even in his merits brief before this Court, Mr.
Carpenter’s discussion of his positive law rights in cell-site
data was cursory. He offered no analysis, for example, of
what rights state law might provide him in addition to
those supplied by §222. In these circumstances, I cannot
help but conclude—reluctantly—that Mr. Carpenter for-
feited perhaps his most promising line of argument.
Unfortunately, too, this case marks the second time this
Term that individuals have forfeited Fourth Amendment
arguments based on positive law by failing to preserve
them. See Byrd, 584 U. S., at ___ (slip op., at 7). Litigants
have had fair notice since at least United States v. Jones
(2012) and Florida v. Jardines (2013) that arguments like
these may vindicate Fourth Amendment interests even
where Katz arguments do not. Yet the arguments have
gone unmade, leaving courts to the usual Katz hand-
waving. These omissions do not serve the development
of a sound or fully protective Fourth Amendment
jurisprudence.