State v. George Steven Burch

2021 WI 68

SUPREME COURT OF WISCONSIN
CASE NO.: 2019AP1404-CR

COMPLETE TITLE: State of Wisconsin,
Plaintiff-Respondent,
v.
George Steven Burch,
Defendant-Appellant.

ON CERTIFICATION FROM THE COURT OF APPEALS

OPINION FILED: June 29, 2021
SUBMITTED ON BRIEFS:
ORAL ARGUMENT: April 12, 2021

SOURCE OF APPEAL:
COURT: Circuit
COUNTY: Brown
JUDGE: John Zakowski

JUSTICES:
HAGEDORN, J., delivered the majority opinion of the Court, in
which ZIEGLER, C.J, ROGGENSACK, and REBECCA GRASSL BRADLEY, JJ.,
joined, and in which DALLET and KAROFSKY, JJ., joined with
respect to Parts I. and II.B. REBECCA GRASSL BRADLEY, J., filed
a concurring opinion. DALLET, J., filed an opinion concurring
in part and dissenting in part, in which KAROFSKY, J., joined
and in which ANN WALSH BRADLEY, J., joined except for footnote
1. ANN WALSH BRADLEY, J., filed a dissenting opinion.
NOT PARTICIPATING:

ATTORNEYS:

For the defendant-appellant, there were briefs filed by Ana
L. Babcock and Babcock Law, LLC. There was an oral argument by
Ana L. Babcock.

For the plaintiff-respondent, there was a brief filed by
Aaron R. O’Neil, assistant attorney general; with whom on the
brief was Joshua L. Kaul, attorney general. There was an oral
argument by Aaron R. O’Neil.
 An amicus curiae brief was filed on behalf of Legal Action
of Wisconsin, Inc. by Rebecca M. Donaldson, Milwaukee.

An amicus curiae brief was filed on behalf of American
Civil Liberties Union Foundation, American Civil Liberties Union
of Wisconsin Foundation, Electronic Frontier Foundation, and
Electronic Privacy Information Center by Laurence J. Dupuis and
American Civil Liberties Union of Wisconsin Foundation,
Milwaukee; with whom on the brief was Jennifer Granick and
American Civil Liberties Union Foundation, San Francisco,
California; with whom on the brief was Jennifer Lynch and
Electronic Frontier Foundation, San Francisco, California.

2
 2021 WI 68
NOTICE
This opinion is subject to further
editing and modification. The final
version will appear in the bound
volume of the official reports.
No. 2019AP1404-CR
(L.C. No. 2016CF1309)

STATE OF WISCONSIN : IN SUPREME COURT

State of Wisconsin,

Plaintiff-Respondent, FILED
v. JUN 29, 2021
George Steven Burch, Sheila T. Reiff
Clerk of Supreme Court
Defendant-Appellant.

HAGEDORN, J., delivered the majority opinion of the Court, in
which ZIEGLER, C.J, ROGGENSACK, and REBECCA GRASSL BRADLEY, JJ.,
joined, and in which DALLET and KAROFSKY, JJ., joined with
respect to Parts I. and II.B. REBECCA GRASSL BRADLEY, J., filed
a concurring opinion. DALLET, J., filed an opinion concurring
in part and dissenting in part, in which KAROFSKY, J., joined
and in which ANN WALSH BRADLEY, J., joined except for
footnote 1. ANN WALSH BRADLEY, J., filed a dissenting opinion.

APPEAL from a judgment of the Circuit Court for Brown

County. Affirmed.

¶1 BRIAN HAGEDORN, J. George Steven Burch appeals a

judgment of conviction for first-degree intentional homicide on

the grounds that two pre-trial evidentiary motions were
incorrectly denied.
 No. 2019AP1404-CR

¶2 First, relying on the Fourth Amendment, Burch moved to

suppress the admission of incriminating cell phone data. This

data was obtained via an unrelated criminal investigation and

kept in a police database. A different law enforcement agency

investigating the homicide came upon this data and used it to

connect Burch to the homicide. Burch argues that the initial

download of the data exceeded the scope of his consent, the data

was unlawfully retained, and the subsequent accessing of the

data violated his reasonable expectation of privacy. We

conclude that even if some constitutional defect attended either

the initial download or subsequent accessing of the cell phone

data, there was no law enforcement misconduct that would warrant

exclusion of that data. Therefore, we conclude the circuit

court correctly denied Burch's motion to suppress that data.

¶3 Regarding the second pre-trial evidentiary motion,

Burch asks us to reverse the circuit court's discretionary

decision to admit evidence from a Fitbit device allegedly worn

by the victim's boyfriend at the time of the homicide. This
evidence, Burch maintains, should have been accompanied by

expert testimony and was insufficiently authenticated. We agree

with the State that the circuit court's decision to admit this

evidence was not an erroneous exercise of discretion. Burch's

judgment of conviction is affirmed.

I. BACKGROUND

¶4 On May 20, 2016, Nicole VanderHeyden went to a bar
with her boyfriend, Douglass Detrie. The two became separated
2
 No. 2019AP1404-CR

and, in the course of a subsequent phone call and text messages,

got into an argument. Detrie returned alone to their shared

home. The next day, VanderHeyden's body was discovered next to

a nearby field. Her blood-stained clothing was later found

discarded alongside a freeway on-ramp, and some of her blood and

hair were identified outside the house of VanderHeyden's

neighbor. The Brown County Sheriff's Office (the "Sheriff's

Office") opened a homicide investigation that spanned the next

several months. Detrie was initially a suspect, but the focus

of the investigation shifted away from Detrie in part because

his Fitbit device logged only 12 steps during the hours of

VanderHeyden's death.1

¶5 While the Sheriff's Office investigated VanderHeyden's

homicide, the Green Bay Police Department (the "Police

Department") undertook an unrelated investigation into three

incidents involving the same vehicle——a stolen vehicle report, a

vehicle fire, and a hit-and-run. George Burch was a suspect in

this investigation, and Police Department Officer Robert
Bourdelais interviewed him on June 8, 2016. Burch denied

involvement and offered the alibi that he was at a bar that

night and texting a woman who lived nearby. As Officer

Bourdelais testified, "I asked [Burch] if I could see the text

messages between him and [the woman], if my lieutenant and I

could take a look at his text messages." Burch agreed. Officer

Detrie wore a Fitbit Flex, a wrist-worn device that
1

continuously tracks the wearer's steps and interfaces with the
wearer's phone or computer.

3
 No. 2019AP1404-CR

Bourdelais then explained that he preferred to download

information off the phone because "it's a lot easier to do that

than try to take a bunch of pictures and then have to scan those

in." "So I asked him if he would be willing to let me take his

phone to this detective, download the information off the phone

and then I'd bring the phone right back to him . . . and he said

that would be fine."

¶6 Before Officer Bourdelais took the phone to be

downloaded, Burch signed a consent form. The form read: "I

George Stephen Burch . . . voluntarily give Det. Danielski,

Officer Bourdelais or any assisting personnel permission to

search my . . . Samsung cellphone." Officer Bourdelais took the

phone and the signed consent form to the certified forensic

computer examiner for the Police Department. The forensic

expert performed a "physical extraction" of all the data on

Burch's phone, brought the data into a readable format, and

saved the extraction to the Police Department's long-term

storage. At a motion hearing, the forensic expert testified
that this was consistent with the Police Department's standard

practice.

¶7 Two months later, two Sheriff's Office detectives

continuing the investigation of VanderHeyden's homicide matched

a DNA sample from VanderHeyden's sock to Burch. The detectives

then searched their own department's records and the records of

other local departments for prior police contacts with Burch.

There they discovered the Police Department's file related to
the three vehicle-related incidents. The file included Burch's
4
 No. 2019AP1404-CR

signed consent form and a copy of the data the Police Department

extracted from Burch's phone during the search. It also

contained a narrative written by Officer Bourdelais which

indicated Burch said Officer Bourdelais "could take his phone to

the department to have the information on it downloaded."

Nothing in the consent form, the narrative, or anything else in

the file, indicated that Burch limited the scope of the data he

consented to have downloaded from his phone.

¶8 The Sheriff's Office detectives reviewed the data

downloaded from Burch's phone. They noted that Burch's internet

history included 64 viewings of news stories about

VanderHeyden's death. And they also discovered Burch had an

email address associated with a Google account. In light of

this discovery, the Sheriff's Office detectives procured a

search warrant to obtain the "Google Dashboard" information from

Google corresponding to Burch's email address. The data Google

provided contained location information that placed Burch's

phone at a bar VanderHeyden visited the night of her death, a
location near VanderHeyden's residence, the place where

VanderHeyden's body was found, and the on-ramp where

VanderHeyden's discarded clothing was discovered.

¶9 Burch was arrested and charged with VanderHeyden's

death. He filed two pre-trial evidentiary motions relevant to

this appeal.

¶10 In one motion, Burch sought to suppress the data

obtained from his cell phone for two reasons: (1) the Police
Department's extraction of the data exceeded the scope of
5
 No. 2019AP1404-CR

Burch's consent by obtaining all the phone's data, rather than

just the text messages; and (2) the Sheriff's Office unlawfully

accessed the data in August 2016. The circuit court2 denied

Burch's motion. It concluded that the conversation between

Burch and Officer Bourdelais did not limit the scope of Burch's

consent, and that "the sharing of such information, without

first obtaining a warrant, is a common and long-understood

practice between related departments."

¶11 Burch also moved to exclude evidence related to

Detrie's Fitbit device. He argued the State must produce an

expert to establish the reliability of the science underlying

the Fitbit device's technology and that the State failed to

sufficiently authenticate the records. The circuit court

disagreed and refused to exclude the Fitbit evidence related to

step-counting.3

¶12 Burch testified in his own defense at trial. He

denied killing VanderHeyden, but acknowledged he was with her

the night she died. According to Burch, he met VanderHeyden at
a bar, and the two left together. After parking near

VanderHeyden's house, they became intimate. That, Burch said,

was the last thing he remembered before waking up on the ground

with Detrie there, and VanderHeyden dead. Burch told the jury

that Detrie held him at gunpoint and instructed him to move

2 The Honorable John P. Zakowski of the Brown County Circuit
Court presided.
3 The circuit court granted Burch's motion in part, agreeing
to exclude Fitbit evidence related to sleep-monitoring.

6
 No. 2019AP1404-CR

VanderHeyden's body into his vehicle, drive to a field, and

carry VanderHeyden's body into the ditch. Only then did Burch

escape by pushing Detrie, running back to his vehicle, and

driving away. Burch added that on his way home he noticed that

articles of VanderHeyden's clothing were still in his vehicle

and threw them out the window in a panic. In the months that

followed, Burch told no one this version of events, even as

authorities sought the public's help in solving VanderHeyden's

homicide.

¶13 The jury found Burch guilty of first-degree

intentional homicide, and the circuit court sentenced him to

life in prison. Burch appealed, challenging the circuit court's

denial of his motion to suppress the cell phone data and his

motion to exclude the Fitbit evidence. The court of appeals

certified the case to us, and we accepted the certification.

II. DISCUSSION

A. Cell Phone Data
¶14 Burch asks us to reverse the circuit court's denial of

his motion to suppress the cell phone data as contrary to the

Fourth Amendment. The Fourth Amendment protects the "right of

the people to be secure in their persons, houses, papers, and

effects, against unreasonable searches and seizures." U.S.

Const. amend. IV. On review of a circuit court's denial of a

suppression motion, we uphold the circuit court's findings of

historical fact unless they are clearly erroneous, and
independently apply constitutional principles to those facts.
7
 No. 2019AP1404-CR

State v. Robinson, 2010 WI 80, ¶22, 327 Wis. 2d 302, 786

N.W.2d 463.

¶15 Before us, Burch argues the cell phone data was

obtained in violation of the Fourth Amendment for three reasons:

(1) the Police Department obtained the data without his consent;

(2) the Police Department unlawfully retained the data after its

investigation into the vehicle-related incidents had ended; and

(3) the Sheriff's Office unlawfully accessed the data in the

Police Department's records without a warrant.4 However, for the

reasons that follow, regardless of whether the data was

unlawfully obtained or accessed, we conclude suppression of the

data is not warranted under the exclusionary rule. See Herring

v. United States, 555 U.S. 135, 139 (2009) (accepting the

"assumption that there was a Fourth Amendment violation" and

analyzing whether the exclusionary rule applied); see also State

v. Kerr, 2018 WI 87, ¶¶20-24, 383 Wis. 2d 306, 913 N.W.2d 787.

1. The Exclusionary Rule
¶16 "When there has been an unlawful search, a common

judicial remedy for the constitutional error is exclusion."

State v. Dearborn, 2010 WI 84, ¶15, 327 Wis. 2d 252, 786

4Burch forfeited his argument related to the Police
Department's retention of the cell phone data by not raising
that argument before the circuit court. See State v. Huebner,
2000 WI 59, ¶10, 235 Wis. 2d 486, 611 N.W. 2d 727. His
arguments regarding the initial download of the data and the
subsequent accessing of the data are, however, properly before
us.

8
 No. 2019AP1404-CR

N.W.2d 97. The exclusionary rule is a judicially-created,

prudential doctrine designed to compel respect for the Fourth

Amendment's constitutional guaranty. Davis v. United States,

564 U.S. 229, 236 (2011). In recent years, the United States

Supreme Court has significantly clarified the purpose and proper

application of the exclusionary rule. See id.; Herring, 555

U.S. 135. In Davis, the Supreme Court explained that prior

cases suggested that the exclusionary rule "was a self-executing

mandate implicit in the Fourth Amendment itself." 564 U.S. at

237. However, more recent cases have acknowledged that the

exclusionary rule is not one of "reflexive" application, but is

to be applied only after a "rigorous weighing of its costs and

deterrence benefits." Id. at 238. Thus, in both Herring and

Davis, the Court explained that to "trigger the exclusionary

rule, police conduct must be sufficiently deliberate that

exclusion can meaningfully deter it, and sufficiently culpable

that such deterrence is worth the price paid by the justice

system." Herring, 555 U.S. at 144; see also Davis, 564 U.S. at
240.

¶17 The "sole purpose" of the exclusionary rule "is to

deter future Fourth Amendment violations." Davis, 564 U.S. at

236-37. Therefore, exclusion is warranted only where there is

some present police misconduct, and where suppression will

appreciably deter that type of misconduct in the future. Id. at

237. The exclusionary rule applies only to police misconduct

that can be "most efficaciously" deterred by exclusion. Id.
(quoting United States v. Calandra, 414 U.S. 338, 348 (1974)).
9
 No. 2019AP1404-CR

Specifically, "the exclusionary rule serves to deter deliberate,

reckless, or grossly negligent conduct, or in some circumstances

recurring or systemic negligence." Herring, 555 U.S. at 144.

"But when the police act with an objectively reasonable good-

faith belief that their conduct is lawful, or when their conduct

involves only simple, isolated negligence, the deterrence

rationale loses much of its force, and exclusion cannot pay its

way." Davis, 564 U.S. at 238 (cleaned up).

¶18 "Real deterrent value is a 'necessary condition for

exclusion,' but it is not 'a sufficient' one." Id. at 237

(quoting Hudson v. Michigan, 547 U.S. 586, 596 (2006)). In

Davis, the Court explained that the "analysis must also account

for the 'substantial social costs' generated by the rule." Id.

(quoting United States v. Leon, 468 U.S. 897, 907 (1984)). It

elaborated:

Exclusion exacts a heavy toll on both the judicial
system and society at large. It almost always
requires courts to ignore reliable, trustworthy
evidence bearing on guilt or innocence. And its
bottom-line effect, in many cases, is to suppress the
truth and set the criminal loose in the community
without punishment. Our cases hold that society must
swallow this bitter pill when necessary, but only as a
"last resort." For exclusion to be appropriate, the
deterrence benefits of suppression must outweigh its
heavy costs.
Id. (citations omitted).

¶19 Applying this rationale, the Supreme Court in Herring

held that a county's failure to update a computer database to

reflect the recall of an arrest warrant was only negligent, and
therefore was "not enough by itself to require 'the extreme

10
 No. 2019AP1404-CR

sanction of exclusion.'" 555 U.S. at 140 (quoting Leon, 468

U.S. at 916). Similarly, in Davis, the Supreme Court refused to

exclude evidence that was obtained via a search conducted in

compliance with binding, but subsequently overruled, precedent.

564 U.S. at 232. Exclusion, it explained, was inappropriate

because it "would do nothing to deter police misconduct." Id.

¶20 We have followed suit as well. In Kerr, we explained

that no police misconduct occurred when an officer conducted an

arrest relying on dispatch's confirmation that the defendant had

a warrant out for his arrest. 383 Wis. 2d 306, ¶22. Exclusion

was improper because "the officers' conduct [was] at most

negligent, and isolated negligence is not 'misconduct' for

purposes of the exclusionary rule." Id. (citing Herring, 555

U.S. at 146-47).

¶21 Many more examples could be provided,5 but the

principle is clear: unless evidence was obtained by

sufficiently deliberate and sufficiently culpable police

misconduct, "[r]esort to the massive remedy of suppressing

5See, e.g., United States v. Leon, 468 U.S. 897, 916 (1984)
(reasonable reliance on a warrant later held invalid); Illinois
v. Krull, 480 U.S. 340, 342 (1987) (reasonable reliance on
subsequently invalidated statutes); Arizona v. Evans, 514
U.S. 1, 15-16 (1995) (reasonable reliance on arrest warrant
information in a database maintained by judicial employees);
State v. Ward, 2000 WI 3, ¶63, 231 Wis. 2d 723, 604 N.W.2d 517
(reasonable reliance on settled law subsequently overruled);
State v. Dearborn, 2010 WI 84, ¶44, 327 Wis. 2d 252, 786
N.W.2d 97 (refusing to exclude evidence where doing so "would
have absolutely no deterrent effect on officer misconduct").

11
 No. 2019AP1404-CR

evidence of guilt is unjustified."6 Hudson, 547 U.S. at 599.

With these principles in mind, we turn to the facts at hand.

2. Application

¶22 In this case, the Sheriff's Office detectives acted by

the book. After a DNA sample from VanderHeyden's sock matched

Burch, officers checked the interdepartmental records already on

file with the police.7 They discovered the two-month-old Police

Department file documenting the investigation for the vehicle-

related incidents. In it, they found and reviewed Burch's

signed consent form and Officer Bourdelais' narrative further

documenting Burch's consent. The Sheriff's Office detectives

observed that neither the consent form nor the narrative listed

any limitations to the scope of consent. And the officers

reviewed the downloaded data, having every reason to think it

was lawfully obtained with Burch's unqualified consent.

¶23 Burch argues that the Sheriff's Office should have

obtained a warrant before accessing the Police Department's

6Failure to apply exclusion is usually described in our
cases as the "good faith" exception to the exclusionary rule.
See, e.g., Dearborn, 327 Wis. 2d 252, ¶4. However, the United
States Supreme Court has called the "good faith" label
confusing. Herring v. United States, 555 U.S. 135, 142 (2009).
The Supreme Court's most recent cases do not use that phrase as
a catchall for cases where exclusion is improper, and do not
describe their conclusion that exclusion was inappropriate as
applying a "good faith" exception. See id. at 147-48; Davis v.
United States, 564 U.S. 229, 249-50 (2011).
7Officers from both the Police Department and the Sheriff's
Office testified that it is common police practice for agencies
to share records with other agencies.

12
 No. 2019AP1404-CR

data. But no case from this court or the federal courts has

suggested that accessing evidence previously obtained by a

sister law enforcement agency is a new search triggering a

renewed warrant requirement.8 Rather, the Sheriff's Office

detectives reasonably relied on Burch's signed consent form and

Officer Bourdelais' narrative to conclude that Burch consented

to the download of the data. They had no reason to think they

were engaging in illegal activity by reviewing interdepartmental

files and evidence. Far from it. Reliance on well-documented

computer records, like the detectives did here, is something the

Supreme Court has characterized as objectively reasonable police

conduct. Arizona v. Evans, 514 U.S. 1, 15-16 (1995). Thus,

there was no misconduct that would "render[] the evidence

suppressible under the exclusionary rule." Kerr, 383

Wis. 2d 306, ¶22.

¶24 Moreover, even if the Sheriff's Office's actions could

be labeled as some kind of misconduct, nothing they did would

rise beyond mere negligence. See id., ¶22 (concluding that "to
the extent that looking at a warrant before executing it may be

8 Justice Dallet's concurrence/dissent argues that courts
should treat cell phone data collected by law enforcement
differently than other types of evidence. It acknowledges that
the sharing of already-collected evidence without a warrant by
sister law enforcement agencies is routine and unproblematic,
but maintains a different kind of analysis should attend cell
phone evidence. We need not decide this question to conclude
exclusion is not warranted in this case. Justice Dallet's
approach would break new ground in Fourth Amendment
jurisprudence, and as such, the violation of her new proposed
rule does not implicate the kind of gross or systemic law
enforcement misconduct the exclusionary rule is meant to deter.

13
 No. 2019AP1404-CR

best practice," failing to do so was "at most negligent");

Herring, 555 U.S. at 140 (holding that a county's failure to

update a computer database was negligent and therefore "not

enough by itself to require" exclusion). And mere negligence

does not warrant suppression. Id. at 144-45.

¶25 In addition, the societal cost of excluding the cell

phone data would far outweigh any deterrence benefit that

exclusion might provide. See Dearborn, 327 Wis. 2d 252, ¶35.

This is in part because there is nothing concerning under

current Fourth Amendment doctrine with how the Sheriff's Office

detectives conducted themselves. Even if the Police

Department's initial download or retention gave cause for

concern, it's not clear what behavior by the Sheriff's Office

Burch would have this court seek to deter.9 Based on the

arguments presented, Burch has given us no reason to deter law

enforcement reliance on the computer records of other law

enforcement agencies. In this case, the societal cost of

Many of Burch's arguments focus on the conduct of the
9

Police Department and the initial download of his cell phone
data. He argues that because the Police Department unlawfully
obtained the data, any subsequent accessing of the data violated
the Fourth Amendment because he retained a reasonable
expectation of privacy in it. But the conduct of the Police
Department has little bearing on whether we should apply the
exclusionary rule against the Sheriff's Office in this case.
The Police Department's involvement in this case was limited to
an investigation of unrelated crimes and was only fortuitously
useful to the Sheriff's Office's investigation of VanderHeyden's
homicide months later. Exclusion therefore would not serve as a
meaningful deterrent for the Police Department and is not
warranted on that basis.

14
 No. 2019AP1404-CR

exclusion would far outweigh the limited benefit——if any——its

application could achieve.

¶26 We conclude that suppression of Burch's cell phone

data is not warranted under the exclusionary rule. Regardless

of whether a constitutional violation occurred, there was no

police misconduct to trigger application of the exclusionary

rule.

B. Fitbit Evidence

¶27 Burch also appeals the circuit court's denial of his

motion to exclude evidence associated with Detrie's Fitbit

device. Burch offers two arguments. First, he argues the

Fitbit evidence must be excluded because the State did not

produce expert testimony to establish its reliability. Second,

he maintains the Fitbit evidence was insufficiently

authenticated.10 We review these evidentiary rulings for an

erroneous exercise of discretion. State v. Nelis, 2007 WI 58,

¶26, 300 Wis. 2d 415, 733 N.W.2d 619.

10Burch also argues that admission of the Fitbit evidence
violates the Confrontation Clause of the Sixth Amendment to the
United States Constitution. Burch concedes, however, that his
novel argument "does not neatly fit within the test set forth in
Crawford v. Washington, 541 U.S. 36 (2004)," and that he raised
the issue solely "to preserve for review before higher courts."
Accordingly, we reject Burch's Confrontation Clause claim and do
not address it further.

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 No. 2019AP1404-CR

1. Expert Testimony

¶28 We have held that that "the requirement of expert

testimony is an extraordinary one" and should apply only "when

the issues before the jury are 'unusually complex or esoteric.'"

State v. Kandutsch, 2011 WI 78, ¶28, 336 Wis. 2d 478, 799

N.W.2d 865 (quoting another source). Before compelling expert

testimony, "the circuit court must first find that the

underlying issue is 'not within the realm of the ordinary

experience of mankind.'" Id. (quoting Cramer v. Theda Clark

Mem'l Hosp., 45 Wis. 2d 147, 150, 172 N.W.2d 427 (1969)). What

falls within the "ordinary experience of mankind," meanwhile,

turns on the circuit court's exercise of its discretion "on a

case-by-case basis" to decide whether "the issue is outside the

realm of lay comprehension" or within the "common knowledge" of

"the average juror." Id., ¶29.

¶29 Burch argues that the Fitbit evidence was improperly

admitted because the circuit court should have required expert

testimony to establish the reliability of the science underlying
Fitbit's technology. He notes that the Fitbit device features

"a three-axis accelerometer sensor that generates data

representing the user's movements," but explains that his

"greater concern is with how the device processes the data into

a meaningful output, how that output is exchanged with a phone

or computer, and how that evidence ultimately ended up in

Fitbit's business records."

¶30 In its written order rejecting Burch's argument that
expert testimony was required, the circuit court explained that
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 No. 2019AP1404-CR

Fitbit's step counters have been in the marketplace since 2009,

and the "principle idea behind pedometers . . . for a

significantly longer period than that." Many smartphones, the

court added, "come equipped with a pedometer by default."

Analogizing to a watch and a speedometer, the court noted that

even though the average juror may not know "the exact mechanics"

of a technology's "internal workings," the public may

nevertheless "generally understand[] the principle of how it

functions and accept[] its reliability." Similarly, the court

reasoned, a Fitbit's use of sophisticated hardware and software

does not render it an "unusually complex or esoteric" technology

because the average juror is nevertheless familiar with what a

Fitbit does and how it is operated.

¶31 This conclusion was reasonable and within the circuit

court's discretionary authority. The circuit court correctly

interpreted the standard for requiring expert testimony and

reasonably applied that standard to the Fitbit evidence before

it. Given the widespread availability of Fitbits and other
similar wireless step-counting devices in today's consumer

marketplace, the circuit court reasonably concluded Detrie's

Fitbit was not so "unusually complex or esoteric" that the jury

needed an expert to understand it.11 The circuit court's

To the extent Burch now argues that the Fitbit is outside
11

the realm of lay comprehension because it is an "internet of
things" device, we are unpersuaded. Wireless technology is
nothing new. It is entirely within the "ordinary experience of
mankind" to use a Bluetooth or Wi-Fi connection to transfer data
from one device to another.

17
 No. 2019AP1404-CR

conclusion that expert testimony was not required under these

circumstances was within the circuit court's discretion.12

2. Authentication

¶32 Wisconsin Stat. § 909.01 (2019-20)13 sets out the

evidentiary standard for authentication: "The requirements of

authentication or identification as a condition precedent to

admissibility are satisfied by evidence sufficient to support a

finding that the matter in question is what its proponent

claims." Simply put, authentication requires that a circuit

court conclude, within its discretion, that the finder of fact

could reasonably determine that the evidence sought to be

admitted is what its proponent says it is. Id.; State v. Smith,

2005 WI 104, ¶¶31-33, 283 Wis. 2d 57, 699 N.W.2d 508. In this

case, that means the State's authentication obligation is to

present sufficient evidence to support a finding that the

records produced by the State are in fact Fitbit's records

associated with Detrie's Fitbit device.
¶33 Notably, Burch does not actually disagree that the

State's records are accurate copies of Fitbit's records

associated with Detrie's Fitbit device. Instead, he focuses his

challenge on whether the State properly authenticated "the

12Of course, opposing counsel may attack the reliability of
admitted evidence. T.A.T. v. R.E.B., 144 Wis. 2d 638, 652-53,
425 N.W.2d 404 (1988).
13All subsequent references to the Wisconsin Statutes are
to the 2019-20 version unless otherwise indicated.

18
 No. 2019AP1404-CR

information within those records." Specifically, he argues that

"the State failed to show that the Fitbit device reliably and

accurately registered Detrie's steps that evening, and that that

data was reliably and accurately transmitted to Fitbit's

business records without manipulation."

¶34 Burch's argument reaches beyond the threshold question

authentication presents. The circuit court's authentication

obligation is simply to determine whether a fact-finder could

reasonably conclude evidence is what its proponent claims it to

be. Wis. Stat. § 909.01. The circuit court did so here by

reviewing the Fitbit records and the affidavit of "a duly

authorized custodian of Fitbit's records" averring that the

records "are true and correct copies of Fitbit's customer data

records," and then concluding the data was self-authenticating

under Wis. Stat. § 909.02(12).14 The circuit court's obligation

is not to scrutinize every line of data within a given record

and decide whether each line is an accurate representation of

the facts. Rather, once the circuit court concludes the fact-
finder could find that the records are what their proponent

claims them to be, the credibility and weight ascribed to those

More precisely, the circuit court held that the records
14

were self-authenticating as certified records of regularly
conducted activity. See Wis. Stat. § 909.02(12). Burch has
not, either before the circuit court or this court, challenged
the statements in the affidavit from Fitbit certifying that the
records it provided are accurate copies of its records
associated with Detrie's Fitbit device.

19
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records are questions left to the finder of fact.15 State v.

Roberson, 2019 WI 102, ¶25, 389 Wis. 2d 190, 935 N.W.2d 813.

The circuit court's conclusion that the Fitbit records were

sufficiently authenticated therefore was within its discretion.

III. CONCLUSION

¶35 Burch's appeal of his conviction for first-degree

intentional homicide challenged the denial of two pre-trial

evidentiary orders. We uphold both orders, and therefore affirm

the judgment of conviction. Burch's cell phone data was

properly admitted because, even if there was some constitutional

defect in how it was obtained or retained, exclusion would be an

improper remedy. The circuit court also permissibly exercised

its discretion in admitting the Fitbit evidence; no expert was

required and the State sufficiently authenticated the records

from Fitbit.

By the Court.——The judgment of the circuit court is

affirmed.

Here, too, opposing counsel can attack the reliability of
15

admitted evidence. See T.A.T., 144 Wis. 2d at 652-53.

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¶36 REBECCA GRASSL BRADLEY, J. (concurring). I join the

majority opinion in full. Because there are no controlling

cases interpreting the Fourth Amendment to prohibit the second

search of Burch's cellphone by the Brown County Sheriff's Office

(Sheriff's Office), the exclusionary rule does not apply and

suppression of the evidence obtained from that search would be

improper.1 I write separately to discuss the application of the

Fourth Amendment to warrantless second searches of smartphones

without consent.

¶37 Under the original meaning of the Fourth Amendment,

law enforcement generally will need a warrant to search the

contents of a smartphone, absent an exception to the warrant

requirement. The consent-to-search exception, which the State

argues authorized law enforcement to conduct a second search of

Burch's smartphone data, does not extend to a second search of a

smartphone by a different law enforcement agency investigating

an entirely separate crime. "Modern cell phones are not just

another technological convenience. With all they contain and
all they may reveal, they hold for many Americans 'the privacies

of life.'" Riley v. California, 573 U.S. 373, 403 (2014)

(quoting Boyd v. United States, 116 U.S. 616, 630 (1886)). The

Fourth Amendment secures "'the privacies of life' against

'arbitrary power,'" and embodies the "central aim of the

Framers . . . 'to place obstacles in the way of a too permeating

1I also agree with the majority that the circuit court did
not erroneously exercise its discretion by admitting evidence
from Douglass Detrie's Fitbit device.

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police surveillance.'" Carpenter v. United States, 138 S. Ct.

2206, 2214 (2018) (quoted sources omitted).

¶38 The contents of smartphones constitute "papers" and

"effects" secured by the Fourth Amendment, giving each of those

categories their historical meanings and bearing in mind that "a

cell phone search would typically expose to the government far

more than the most exhaustive search of a house." Riley, 573

U.S. at 396. Accordingly, law enforcement generally must get a

warrant before searching a cell phone. Id. at 403. Because

Burch's consent to search covered only the Green Bay Police

Department's initial search of his smartphone for evidence

related to a hit-and-run investigation, a warrant should have

been procured before the Sheriff's Office searched Burch's

smartphone data as part of an unrelated murder investigation.

Because neither this court nor the United States Supreme Court

has decided this novel issue, the Sheriff's Office committed no

misconduct in searching Burch's cell phone and the circuit court

properly admitted the evidence obtained from the search.
Accordingly, I respectfully concur.

I

¶39 In June 2016, a few weeks after Nicole VanderHeyden's

murder and the ensuing investigation by the Sheriff's Office,

the Green Bay Police Department (Police Department) began

investigating an entirely unrelated crime: an auto theft that

resulted in a hit-and-run incident.2 The stolen car belonged to

Burch's roommate, and law enforcement identified Burch as a

2 The vehicle was also lit on fire.

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person of interest because he had last driven the car. Officer

Robert Bourdelais of the Police Department interviewed Burch

about the hit and run. Burch denied any involvement, but

informed Officer Bourdelais that, on the night of the hit and

run, he was texting a woman who lived one block away from the

location of the accident. Burch stated that he did not go to

the woman's house on the night of the incident, and never made

arrangements to go to her house. According to Officer

Bourdelais' testimony, he and Burch had the following exchange:

I asked him if I could see the text messages between
him and [the woman], if my lieutenant and I could take
a look at his text messages. He said that we
could . . . . I [then] asked him if he would be
willing to let me take his phone to this detective,
download the information off the phone and then I'd
bring the phone right back to him, probably take a
half an hour and he said that would be fine.
¶40 The attorney eliciting Officer Bourdelais' testimony

inquired: "When you asked [Burch] about downloading the

information off of his phone, did you specifically limit the

information to the text messages when you were talking to him?"

Officer Bourdelais responded:

No, I didn't. Initially, when I had asked him, hey,
do you mind if we take a look at those text messages,
I refer to them as text messages because he said he
was texting [the woman] back and forth, but from my
experience as a police officer I know people
communicate [by] phone calls, text messages, texting
apps like WhatsApp, MINE, Facebook Messenger, things
like that. So that's the information, I wanted
information to corroborate that whatever conversation
he had with [the woman] or communication he had
supported his claims that he never went over to her
house or made arrangements to go over to her house.

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¶41 Following the exchange between Burch and Officer

Bourdelais, Burch signed a consent form which read as follows:

"I, George Stephen Burch, . . . voluntarily give Det. Danielski,

Officer Bourdelais, or any assisting personnel permission to

search my . . . Samsung cellphone." Subsequently, at the

instruction of Officer Bourdelais, a Police Department forensic

examiner downloaded all of the data from Burch's cellphone into

the Police Department records database. The forensic examiner

then converted the data into a readable format, and tabbed the

data into categories such as text messages, images, and internet

history. At the homicide trial, the forensic examiner testified

that the Police Department retains smartphone data for an

indefinite amount of time, noting that "[e]ver since [she] [has]

been employed with [the Police Department], [they] have saved

all extractions for long-term storage for as far back as [she]

[has] been employed," which was roughly two years at the time of

trial.

¶42 In August 2016 (two months after Burch consented to
the search of his phone for the hit-and-run investigation), the

Sheriff's Office identified Burch as a person of interest in the

investigation into the murder of VanderHeyden based upon a DNA

match on VanderHeyden's socks. Relying on databases shared

between the Sheriff's Office and other local entities,

detectives from the Sheriff's Office discovered that the Police

Department had prior contact with Burch while investigating the

unrelated hit-and-run incident. After the detectives learned
that the Police Department had extracted all of Burch's

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smartphone data in June 2016, they procured a copy of the data

from the Police Department and searched its contents "for

anything in the timeframe of the night of [the murder] into the

[following] morning, whether it be calls, texts, internet

history, any kind of location data available from that device."

The detectives did not obtain a warrant for this search. In

reviewing the data, the detectives discovered that, shortly

after the murder, Burch repeatedly searched for news articles

about the murder using his internet browser.

¶43 Additionally, during their warrantless search of the

smartphone's contents, the detectives learned that Burch had a

Google email account (Gmail). The detectives were aware that

Gmail addresses are associated with a Google Dashboard, which

tracks an individual's location based upon GPS, Wi-Fi, and

cellphone tower data. The detectives procured a search warrant

to obtain Google Dashboard information from Google. The

location data placed Burch's smartphone at various critical

places on the night of the murder, including the location of
VanderHeyden's body and the on-ramp where her discarded clothing

was discovered.

¶44 Burch was arrested and charged with first-degree

intentional homicide. In a pre-trial motion, Burch moved to

suppress the evidence obtained by the Sheriff's Office from the

warrantless search of his smartphone data.3 Burch argued that

the Sheriff's Office "violated the Fourth Amendment when [it]

Burch also filed a motion to exclude evidence related to
3

Detrie's Fitbit device, which the circuit court denied.

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searched the phone data initially seized by [the Police

Department]." Specifically, Burch contended that the Sheriff's

Office "blew past Mr. Burch's scope of consent, and likewise,

obliterated any Fourth Amendment warrant exceptions." The

circuit court denied Burch's suppression motion, and the State

introduced at trial the evidence obtained from the smartphone.

The jury convicted Burch of first-degree intentional homicide.

Burch appealed the circuit court's decision to admit the

evidence procured by the Sheriff's Office from its search of his

smartphone data. The court of appeals certified Burch's Fourth

Amendment challenge to this court, and we accepted

certification.

II

¶45 The Fourth Amendment provides:

The right of the people to be secure in their persons,
houses, papers, and effects, against unreasonable
searches and seizures, shall not be violated, and no
Warrants shall issue, but upon probable cause,
supported by Oath or affirmation, and particularly
describing the place to be searched, and the persons
or things to be seized.
U.S. Const. amend. IV. "The first clause outlaws promiscuous

search and seizure, even as the second clarifies precisely what

will be required for a particularized warrant to be valid."

Laura K. Donohue, The Original Fourth Amendment, 83 U. Chi. L.

Rev. 1181, 1193 (2016); State v. Pinder, 2018 WI 106, ¶¶48-51,

384 Wis. 2d 416, 919 N.W.2d 568. As understood at the time the

Fourth Amendment was ratified, "[t]he government could not

violate the right against search and seizure of one's person,
house, papers, or effects absent either a felony arrest or a
6
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warrant meeting the requirements detailed in the second clause."

Donohue, supra, at 1193.

¶46 As the United States Supreme Court has repeatedly

held, "the ultimate touchstone of the Fourth Amendment is

'reasonableness.'" Brigham City v. Stuart, 547 U.S. 398, 403

(2006). "[W]hether an individual has a reasonable expectation

of privacy in avoiding the method of search and

a reasonable expectation of privacy in the place searched are

the questions that drive a court's examination of the

reasonableness of the search." State v. Brereton, 2013 WI 17,

¶32, 345 Wis. 2d 563, 826 N.W.2d 369. "The general rule is that

searches and seizures conducted without a warrant are not

reasonable." State v. Randall, 2019 WI 80, ¶10, 387

Wis. 2d 744, 930 N.W.2d 223. However, there are a number of

exceptions to the warrant requirement. See Riley, 573 U.S. at

382 ("In the absence of a warrant, a search is reasonable only

if it falls within a specific exception to the warrant

requirement."). "One of the exceptions to the warrant rule is
that an individual's consent to search satisfies the

constitutional 'reasonableness' requirement." Randall, 387

Wis. 2d 744, ¶10; see also Birchfield v. North Dakota, 136 S.

Ct. 2160, 2185 (2016) ("It is well established that a search is

reasonable when the subject consents[.]"). "If a search is

premised on an individual's consent, it must cease immediately

upon revocation of that consent," and an individual "may of

course delimit as she chooses the scope of the search to which

7
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she consents." Randall, 387 Wis. 2d 744, ¶10 (internal

alterations and citations omitted).

¶47 Just a few years ago, the United States Supreme Court

addressed the Fourth Amendment's application to a modern

phenomenon: the proliferation of smartphones and their ever-

increasing capacity to store mass amounts of data. The Court

held that law enforcement generally must obtain a warrant before

conducting a search of smartphone data. Specifically, the Riley

Court clarified that "[its] holding . . . is not that the

information on a cell phone is immune from search," but "instead

that a warrant is generally required before such a search, even

when a cell phone is seized incident to arrest."4 Riley, 573

U.S. at 401. In reaching this holding, the Court recognized the

"pervasiveness that characterizes cell phones" and how "[c]ell

phones differ in both a quantitative and a qualitative sense

from other objects." Id. at 393, 395. "The possible intrusion

on privacy is not physically limited in the same way [as other

objects] when it comes to cell phones." Id. at 394. "An
internet search and browsing history, for example, can be found

on an internet-enabled phone and could reveal an individual's

private interests or concerns," and "historic location

4Although Riley involved the search-incident-to-arrest
exception to the Fourth Amendment warrant requirement, the
principles it espouses apply more broadly. See Riley v.
California, 573 U.S. 373, 386 (2014) ("[O]fficers must generally
secure a warrant before conducting such a search [of a cell
phone]."); see also People v. Hughes, 958 N.W.2d 98, 108 (Mich.
2020) ("In Riley v. California, the Supreme Court of the United
States held that officers must generally obtain a warrant before
conducting a search of cell-phone data.").

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information" could allow law enforcement to "reconstruct

someone's specific movements down to the minute." Id. at 395-

96.

¶48 The United States Supreme Court fully understood that

its decision "[would] have an impact on the ability of law

enforcement to combat crime." Id. at 401. After all, "[c]ell

phones have become important tools in facilitating coordination

and communication" for individuals committing crimes and "can

provide valuable incriminating information about dangerous

criminals." Id. But "[p]rivacy comes at a cost." Id. And the

Fourth Amendment is designed to safeguard the people's security

against unreasonable government intrusion. Riley recognizes

that the Fourth Amendment safeguards this right by generally

requiring law enforcement to procure a warrant before searching

a smartphone.

¶49 A warrant requirement for searches of smartphone data

comports with the original meaning of the Fourth Amendment. The

Framers, "after consulting the lessons of history, designed our
Constitution to place obstacles in the way of a too permeating

police surveillance, which they seemed to think was a greater

danger to a free people than the escape of some criminals from

punishment." United States v. Di Re, 332 U.S. 581, 595 (1948).

In particular, "the Fourth Amendment was the founding

generation's response to the reviled 'general warrants' and

'writs of assistance' of the colonial era, which allowed British

officers to rummage through homes in an unrestrained search for
evidence of criminal activity. Opposition to such searches was

9
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in fact one of the driving forces behind the Revolution itself."

Riley, 573 U.S. at 403. "Indeed, the character of that threat

implicates the central concern underlying the Fourth Amendment——

the concern about giving police officers unbridled discretion to

rummage at will among a person's private effects." Arizona v.

Gant, 556 U.S. 332, 345 (2009). For the Framers, it was

absolutely necessary to ensure "the government not be allowed

free rein to search for potential evidence of criminal

wrongdoing." Donohue, supra, at 1194.

¶50 The Framers designed the Fourth Amendment to protect

the people from government overreach. Described as the "very

essence of constitutional liberty and security," the Fourth

Amendment applies to "all invasions on the part of the

government and its employes of the sanctity of a man's home and

the privacies of life." Boyd, 116 U.S. at 630. "It is not the

breaking of [one's] doors, and the rummaging of his drawers,

that constitutes the . . . offense; but it is the invasion of

his infeasible right of personal security, personal liberty, and
private property[.]" Id. With this understanding in mind,

"[t]he Supreme Court has . . . confirmed that the basic purpose

of the Fourth Amendment 'is to safeguard the privacy and

security of individuals against arbitrary invasions by

governmental officials'"——that is, "to secure 'the privacies of

life' against 'arbitrary power.'" Matthew DeVoy Jones, Cell

Phones are Orwell's Telescreen: The Need for Fourth Amendment

Protection in Real-Time Cell Phone Location Information, 67

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Clev. St. L. Rev. 523, 533 (2019) (quoting Carpenter, 138 S. Ct.

at 2213-14).

¶51 The Fourth Amendment specifically recognizes the right

of people to be secure in their "persons, houses, papers, and

effects." U.S. Const. amend. IV; see United States v. Jones,

565 U.S. 400, 406 (2012) ("[F]or most of our history the Fourth

Amendment was understood to embody a particular concern for

government trespass upon the areas ('persons, house, papers, and

effects') it enumerates."). Much modern analysis of the Fourth

Amendment has centered upon the primacy of protecting "houses."

See Payton v. New York, 445 U.S. 573, 589 (1980) ("The Fourth

Amendment protects the individual's privacy in a variety of

settings. In none is the zone of privacy more clearly defined

than when bounded by the unambiguous physical dimensions of an

individual's home[.]"). However, as the Riley Court explained,

smartphones implicate privacy interests more compelling than

even those associated with the home. "A cell phone search would

typically expose to the government far more than the most
exhaustive search of a house: A phone not only contains in

digital form many sensitive records previously found in the

home; it also contains a broad array of private information

never found in a home in any form[.]" Riley, 573 U.S. at 396-

97.

¶52 Given the nature of its contents, a smartphone is not

just another personal item; it is a device that holds many

modern "privacies of life"——an area that receives acute and
particularized protection from government interference under the

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Fourth Amendment. See Boyd, 116 U.S. at 630. Governmental

searches of smartphones invade "the indefeasible right of

personal security, personal liberty, and private property,"

which Americans hold "sacred." Id. Permitting law enforcement

to rummage through the data residing in smartphones without a

warrant would "allow[] free rein to search for potential

evidence of criminal wrongdoing," which the Fourth Amendment

prohibits. With respect to smartphone data, as in the home,

"all details are intimate details, because the entire area is

held safe from prying government eyes." See Kyllo v. United

States, 533 U.S. 27, 37 (2001).

¶53 The Fourth Amendment includes both "papers" and

"effects" among the four enumerated categories protected from

unreasonable searches. The contents of smartphones constitute

"papers" within the original understanding of the Fourth

Amendment. "Historically, private papers, including documents

and pamphlets that challenged governmental power, served as a

central point of contestation in the Founding era." Andrew
Guthrie Ferguson, The "Smart" Fourth Amendment, 102 Cornell L.

Rev. 547, 595-96 (2017). The Fourth Amendment's protection of

"papers" "reflect[s] the importance of freedom of thought,

expression, and communication." Id. According to Lord Camden

in his seminal decision in Entick v. Carrington, "papers are

often the dearest property a man can have." 19 How. St. Tr.

1029 (C.P. 1765).

¶54 The Framers' inclusion of "papers" within the
protections of the Fourth Amendment was motivated in part by the

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case of John Wilkes, "who was targeted for writing mocking

articles about King George III" and had his papers seized by

investigating officers. Ferguson, supra, at 596 (citation

omitted). "The Wilkes controversy . . . directly influenced the

[F]ramers of the Fourth Amendment. The English search and

seizure cases received extensive publicity in England and in

America, and the Wilkes case was the subject of as much

notoriety and comment in the colonies as it was in Britain."

Eric Schnapper, Unreasonable Searches and Seizures of Papers, 71

Va. L. Rev. 869, 912-13 (1985). "Wilkes' cause generated many

supporters among American colonists, some of whom became key

figures in the framing of the Constitution." Id. at 913. Based

upon Wilkes' case, "[p]rotecting private papers . . . became a

central rallying cry in the creation of constitutional liberty,"

receiving explicit protection under the United States

Constitution. Ferguson, supra, at 596.

¶55 Today, the people's "papers" largely exist in digital

form. "E-mails, texts, and other social media communication
have replaced letter writing." Id. at 599. Additionally,

calendars, notes, health information, photographs, restaurant

and hotel reservations, airline flights, shopping and browsing

histories, as well as banking transactions all reside in (or are

accessible from) smartphones, forming a digital diary of one's

life, accessible from a single source. Given the breadth and

detail of this information, "individuals have expectations of

privacy in their digital papers." Id. at 600. From the
Framers' outrage over the search of Wilkes' papers to the

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Court's concern regarding the search of David Riley's

smartphone, the overarching aim "has always been the protection

of ideas embodied in those papers"——not whether the papers are

in physical or digital form. Id. at 613.

¶56 Some portion of the contents of smartphones, as well

as the devices themselves, also constitute "effects," which

"have historically been understood to mean personal property——

the objects we possess." Id. at 578 (citing Dictionarium

Brittanicum (Nathan Baily ed., 1730) (defining "effects" as "the

goods of a merchant, tradesman") and Noah Webster, First Edition

of an American Dictionary of the English Language (1828)

(defining "effects" as "goods; moveables; personal estate")).

"The early American understanding distinguished personal

property from real property," and "personal property meant

physical belongings"——items which were "obviously prized by the

Founders" and accordingly received Fourth Amendment protection.

Id. Founding-era history "demonstrates that effects were

specifically included in the constitutional text [not only]
because of the harms to privacy and dignity that could be

incurred in their inspection, but also because of the risk of

mishandling or damage generally associated with interferences

with personal property." Maureen E. Brady, The Lost "Effects"

of the Fourth Amendment: Giving Personal Property Due

Protection, 125 Yale L.J. 946, 987 (2016). Founding-era sources

suggest the Framers understood "[p]ersonal property [to] give[]

its owner a right to exclude others from possessing, using, and
interfering with the effect"——and most of all to "protect[]

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privacy interests with respect to the property." Id. at 993-94

(discussing founding-era sources, including William Blackstone's

Commentaries and Lord Camden's judgment in Entick v.

Carrington).

¶57 Although "'effects' has captured rather less of the

[United States] Supreme Court's attention" than "papers" and

"houses," when the Court has addressed the topic, "property

considerations loom large." Laura K. Donohue, The Fourth

Amendment in a Digital World, 71 N.Y.U. Ann. Surv. Am. L. 553,

679 (2017). For example, in United States v. Jones, the United

States Supreme Court held that law enforcement's installation of

a GPS device on an individual's vehicle to monitor the vehicle's

movements constituted a "search" under the Fourth Amendment,

deeming it "beyond dispute" that a vehicle is an "effect" within

the meaning of the Fourth Amendment. 565 U.S. 400, 404 (2012).

The Court emphasized the government's "physical intrusion" of

the "effect" at issue. Id. at 411. The Court did not focus on

the physical attachment of the GPS device to the effect but
rather the device's capture of sensitive and private

information, "relay[ing] more than 2,000 pages of data over [a]

4-week period." Id. at 403; see also Ferguson, supra, at 606

("[In Jones] the real harm was exposing the revealing personal

data about the effect (car)."). That is, in Jones the Fourth

Amendment analysis turned on the "capturing of data trails" of

the owner and "invad[ing] the informational security of the

effect." Ferguson, supra, at 606. The Court's reasoning in
Jones applies no less to smartphones and the data they hold,

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supporting the characterization of smartphones as "effects"

entitled to constitutional protection from unreasonable searches

and seizures.

III

¶58 Having established a historical basis for the

application of the Fourth Amendment's warrant requirement to

smartphones and their data, it is necessary to address the

application of the consent exception to the warrant requirement

within the context of the facts of Burch's case. It is well-

established that "[o]ne of the exceptions to the warrant rule is

that an individual's consent to search satisfies the

constitutional 'reasonableness' requirement." Randall, 387

Wis. 2d 744, ¶10; see also Birchfield, 136 S. Ct. at 2185.

Burch gave consent for the Police Department to download and

search his smartphone and its data as part of the investigation

of the hit-and-run incident in June 2016. According to his

testimony, Officer Bourdelais asked Burch if "[he] could see the

text messages between him and [the woman]" on the night of the
hit-and-run incident. Officer Bourdelais then asked Burch if he

could "take his phone to this detective, download the

information off the phone" and then bring it right back to

Burch. Burch agreed to all requests in this exchange and signed

a consent form saying he "voluntarily give[s] Det. Danielski,

Officer Bourdelais, or any assisting personnel permission to

search [his] . . . Samsung cellphone." Burch permitted Officer

Bourdelais "or any assisting personnel" to download his
smartphone's data and search for evidence of the hit-and-run

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incident. Burch's consent encompassed the Police Department's

investigation of a particular crime. The Constitution permitted

this search. Schneckloth v. Bustamonte, 412 U.S. 218, 222

(1973) ("[A] search conducted pursuant to a valid consent is

constitutionally permissible.").

¶59 Two months later, a different law enforcement agency——

the Sheriff's Office——searched Burch's smartphone data while

investigating an entirely separate crime. This search went

beyond the scope of Burch's consent. Officer Bourdelais

questioned Burch in June 2016 regarding the hit-and-run incident

only, and obtained Burch's consent to download Burch's

smartphone data "[to] corroborate that whatever conversation

[Burch] had with [the woman] . . . supported his claims that he

never went over to her house" the night of the hit and run. The

consent form did not include any language authorizing a second

search by a separate law enforcement agency for a different

crime. The form authorized only Officer Bourdelais, the

forensic examiner (Det. Danielski), and their assisting
personnel to view the smartphone's contents. Any search beyond

the scope of Burch's consent would require a warrant.

¶60 The State argues that this court's decision in State

v. Betterley, 191 Wis. 2d 406, 529 N.W.2d 216 (1995), allows law

enforcement to take a "second look" at smartphone data that was

previously searched. That case does not apply to searches of

cell phone data. In Betterley, officers at the St. Croix County

Jail seized a ring from the defendant during an inventory
search. Id. at 414. Later that day, a New Richmond police

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officer asked to see the ring, believing it was evidence that

the defendant had committed insurance fraud. Id. at 415. The

New Richmond police officer retained the ring as evidence

without obtaining a warrant. Id. This court held that "the

permissible extent of the second look [at evidence] is defined

by what the police could have lawfully done without violating

the defendant's reasonable expectations of privacy during the

first search, even if they did not do it at that time." Id. at

418. Because the defendant had a diminished expectation in

privacy in the ring after forfeiting it during the first search,

the second look at the ring was permissible, so long as it was

"no more intrusive" than the first search. Id.

¶61 Betterley does not apply to cell phone data retrieved

pursuant to the owner's consent. Betterley involved an

inventory search of an item, not the consent-to-search exception

to the warrant requirement. Unlike searches conducted with

consent, inventory searches are "administrative by nature, not

an investigation motivated by a search for evidence." State v.
Weber, 163 Wis. 2d 116, 132, 471 N.W.2d 187 (1991). More

importantly, physical items such as rings are qualitatively

different than searches of smartphone data. Examination of a

ring reveals nothing more than the physically observable item

itself, while smartphones contain——and conceal——the "privacies

of life," which generally are not viewable by others at a

glance. For this reason, smartphones "differ in both a

quantitative and a qualitative sense from other objects."
Riley, 573 U.S. at 393. "[I]t is no exaggeration to say that

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many of the more than 90% of American adults who own a cell

phone keep on their person a digital record of nearly every

aspect of their lives——from the mundane to the intimate.

Allowing the police to scrutinize such records on a routine

basis is quite different from allowing them to search a personal

item or two in the occasional case." Id. at 395. Certainly,

"the possible intrusion on privacy is not physically limited in

the same way [as other objects] when it comes to cell phones."

Id. at 394. Accordingly, Betterley does not inform the Fourth

Amendment analysis governing searches of cell phone data.

¶62 Even if "a Fourth Amendment violation has occurred,"

however, it "does not mean the exclusionary rule applies,"

particularly because "exclusion [of evidence] is the last

resort." State v. Dearborn, 2010 WI 84, ¶35, 327 Wis. 2d 252,

786 N.W.2d 97. "To trigger the exclusionary rule, police

misconduct must be sufficiently deliberate that exclusion can

meaningfully deter it, and sufficiently culpable that such

deterrence is worth the price paid by the justice system." Id.,
¶36 (quoted source omitted). For the reasons stated in the

majority opinion, there was no misconduct by the Sheriff's

Office. Neither this court nor the United States Supreme Court

has declared that second searches of cell phone data by separate

law enforcement agencies require a warrant. Accordingly,

suppression of the evidence obtained during the Sheriff's

Office's second search would be inappropriate and I respectfully

concur.

19
 No. 2019AP1404-CR.rgb

* * *

¶63 "The great end, for which men entered into society,

was to secure their property." Entick v. Carrington, 19 How.

St. Tr. 1029 (C.P. 1765) (Lord Camden presiding). "Property

must be secured, or liberty cannot exist." Discourses on

Davila, in 6 The Works of John Adams 280 (C. Adams ed. 1851).

"The Fourth Amendment imposes limits on search-and-seizure

powers in order to prevent arbitrary and oppressive interference

by enforcement officials with the privacy and personal security

of individuals." United States v. Martinez-Fuerte, 428 U.S.

543, 554 (1976). Because smartphones contain the "privacies of

life," law enforcement generally needs a warrant to search the

data they hold unless an exception to the warrant requirement

applies.

20
 No. 2019AP1404-CR.rfd

¶64 REBECCA FRANK DALLET, J. (concurring in part,

dissenting in part). Under the Fourth Amendment, when the

police want to search a person's private information, they

generally need a warrant. The Brown County Sheriff's Office

searched George Steven Burch's private cell phone data without

obtaining a warrant, assuming that Burch's consent for another

agency to download his phone's data for a wholly separate

investigation obviated its Fourth Amendment duty to do so. It

did not. The Sheriff's Office's warrantless search of Burch's

cell phone data violated the Fourth Amendment, and the evidence

obtained from that unlawful search should be suppressed. The

majority opinion's contrary holding ignores the novel

constitutional problems presented by private cell phone

information, is inconsistent with the Fourth Amendment's text,

and undermines the exclusionary remedy for Fourth Amendment

violations. I therefore respectfully dissent from that part of

the majority opinion.1

I. BACKGROUND
¶65 A Green Bay Police Department (GBPD) officer

interviewed Burch while investigating crimes involving the car

Burch would borrow for work. Burch denied his involvement but

acknowledged that he was text messaging a friend that night who

lived near the scene. When the officer asked Burch if he and

his lieutenant could see those text messages, Burch verbally

consented. After the officer explained that it was easier to

1I join Parts I. and II.B. of the majority opinion because
I agree that the circuit court permissibly admitted evidence
regarding a Fitbit device.

1
 No. 2019AP1404-CR.rfd

download "the information" from the phone than to take

screenshots, Burch verbally consented to allowing the officer to

take his phone to a GBPD detective for that purpose.2 The

officer then presented Burch with a standardized written consent

form. The form contained the heading "City of Green Bay Police

Department" and indicated that Burch "voluntarily" gave a named

GBPD officer, a named GBPD detective, as well as any "assisting

personnel," "permission to search" his "Samsung Cellphone."

Burch signed the form. The officer testified that he requested

only "text messages, phone calls, Facebook posts, and

photographs taken any time after 11:00 p.m." the night of the

accident; yet, to access that information, the GBPD downloaded

the entire contents of Burch's phone.

¶66 Two months later, the Sheriff's Office was

investigating a homicide that had occurred a few weeks before

the crimes being investigated by the GBPD. It matched Burch's

DNA to DNA collected from the victim's body, her socks, and a

cord believed to be used in her murder. The Sheriff's Office

At trial, the officer testified that by "the information,"
2

he meant any communications between Burch and his friend that
would corroborate Burch's alibi:

Initially, when I had asked [Burch], hey, do you mind
if we take a look at those text messages, I refer to
them as text messages because he said he was texting
[his friend] back and forth, but from my experience as
a police officer I know people communicate phone
calls, text messages, texting apps like WhatsApp,
MINE, Facebook Messenger, things like that. So that's
the information, I wanted information to corroborate
that whatever conversation he had with [his friend] or
communication he had supported his claims that he
never went over to [the victim's] house or made
arrangements to go over to her house.

2
 No. 2019AP1404-CR.rfd

also discovered that the GBPD had retained the full data

extraction from Burch's cell phone. After reviewing the GBPD's

files and seeing Burch's signed consent form, the Sheriff's

Office searched that data without first obtaining a warrant.

The search led the Sheriff's Office to Burch's internet search

history and his Google email account. The internet history

revealed that Burch had viewed online stories about the victim's

disappearance 64 times. The email account allowed the Sheriff's

Office to issue Google a subpoena for Burch's Google Dashboard

records, which included his location data from the night of the

murder. The location data placed Burch's cell phone near the

victim's residence and the field where her body was discovered

around the time of the victim's death.

II. ANALYSIS

¶67 The Fourth Amendment inquiry here is two-fold. The

first consideration is whether the Sheriff's Office's

warrantless search of the GBPD's download of Burch's data was

unreasonable. If so, it violated the Fourth Amendment, and the
question becomes whether excluding the unlawfully obtained

evidence would sufficiently deter the same police conduct in the

future. These questions involve a mixed standard of review,

under which we uphold the circuit court's findings of historical

fact unless they are clearly erroneous, but we review de novo

the application of constitutional principles to those facts.

See State v. Blackman, 2017 WI 77, ¶25, 377 Wis. 2d 339, 898
N.W.2d 774.

3
 No. 2019AP1404-CR.rfd

A. The Sheriff's Office's Warrantless Search Was Unreasonable.

¶68 The Fourth Amendment to the United States Constitution

prohibits the government from conducting "unreasonable" searches

of a person, a person's home, or her "effects":

The right of the people to be secure in their persons,
houses, papers, and effects, against unreasonable
searches and seizures, shall not be violated, and no
warrants shall issue, but upon probable cause . . . .
The Amendment seeks to secure "the privacies of life" against

such unreasonable searches by placing "obstacles in the way of a

too permeating police surveillance." See Carpenter v. United

States, 585 U.S. ___, 138 S. Ct. 2206, 2214 (2018). Police

surveillance amounts to a "search," for purposes of the Fourth

Amendment, when it collects information in which the person has

a reasonable expectation of privacy. E.g., id. at 2213-14.

¶69 To protect one's reasonable expectation of privacy,

the text of the Fourth Amendment communicates a "strong

preference for searches conducted pursuant to a warrant." See

Illinois v. Gates, 462 U.S. 213, 236 (1983); U.S. Const.

amnd. IV. Indeed, a warrantless search is per se unreasonable,
see Schneckloth v. Bustamonte, 412 U.S. 218, 219 (1973), and

presumptively violates the Fourth Amendment, see State v.

Tate, 2014 WI 89, ¶27, 357 Wis. 2d 172, 849 N.W.2d 798. That

presumption is overcome only when the warrantless search falls

under one of the "few specifically established and well-

delineated exceptions." State v. Coffee, 2020 WI 53, ¶24, 391

Wis. 2d 831, 943 N.W.2d 845.
¶70 Consent is one such exception. State v. Hogan, 2015

WI 76, ¶55, 364 Wis. 2d 167, 868 N.W.2d 124. As with any

4
 No. 2019AP1404-CR.rfd

exception to the warrant requirement, consent is "jealously and

carefully drawn," and must be "confined in scope" and "strictly

circumscribed." See Jones v. United States, 357 U.S. 493, 499

(1958); Terry v. Ohio, 392 U.S. 1, 25-26, 29 (1968). Consent to

a particular search must therefore be "unequivocal and

specific." State v. Reed, 2018 WI 109, ¶8, 384 Wis. 2d 469, 920

N.W.2d 56. Even absent express limits, the scope of consent is

neither "boundless" nor "perpetual." See State v. Douglas, 123

Wis. 2d 13, 21-22, 365 N.W.2d 580 (1985) (lead opinion).

Rather, its scope is determined objectively as "the typical

reasonable person [would] have understood" it from "the exchange

between the officer and the suspect." Florida v. Jimeno, 500

U.S. 248, 251 (1991). When the police rely on consent as their

justification for not getting a warrant, the State carries the

burden to demonstrate by clear and convincing evidence that the

search remained within the scope of that consent. See Reed, 384

Wis. 2d 469, ¶58; Douglas, 123 Wis. 2d at 22 (explaining that a

warrantless search exceeding the scope of consent is
unreasonable).

¶71 The lawfulness of the Sheriff's Office's search

therefore turns on two sub-questions: (1) although he consented

to specific GBPD personnel downloading his cell phone

information, did Burch maintain a reasonable expectation of

privacy in that information such that the Sheriff's Office

review of it was a Fourth Amendment search; and, if so, (2) did

the Sheriff's Office act unreasonably by searching the GBPD's
download of Burch's cell phone data without a warrant, in light

of Burch's consent to the GBPD?

5
 No. 2019AP1404-CR.rfd

1. Burch Maintained a Reasonable Expectation of Privacy in the
GBPD's Download of His Cell Phone Data.
¶72 In the Fourth Amendment context, the United States

Supreme Court has clearly expressed that cell phone data is in

an evidence class of its own because it "implicate[s] privacy

concerns far beyond those implicated by the search of" other

physical belongings. Riley v. California, 573 U.S. 373, 393

(2014). Cell phones are unique in that they are almost always

with us and they store "vast quantities of personal

information." Id. at 386. Thus, by carrying cell phones,

people carry with them "a digital record of nearly every aspect

of their lives——from the mundane to the intimate." Id. at 395.

That digital record may include a person's internet "search and

browsing history" and "[h]istoric location information," see id.

at 395-96, allowing someone with access to that information to

"generate[] a precise, comprehensive record of a person's public

movements that reflects a wealth of detail about her familial,

political, professional, religious, and sexual associations,"

see United States v. Jones, 565 U.S. 400, 415 (2012)

(Sotomayor, J., concurring). Although traditionally most

private information was kept in one's home, advances in digital

technology have shifted that paradigm such that searching a

personal cell phone "would typically expose to the government

far more than the most exhaustive search of a house."

Riley, 573 U.S. at 396-97. Accordingly, people have a unique

and heightened expectation of privacy in their cell phone data

that demands commensurate Fourth Amendment protection. See id.
at 386, 393; People v. Hughes, 958 N.W.2d 98, 112 (Mich. 2020)

6
 No. 2019AP1404-CR.rfd

("Riley distinguished cell-phone data from other items . . . in

terms of the privacy interests at stake.").

¶73 The unique privacy expectation in cell phone data

informs why Burch's consent to the GBPD does not relieve the

Sheriff's Office of its obligation to get a warrant for its own

review. Burch's consent, as "the typical reasonable person

[would] have understood" it, had the "expressed object" of the

GBPD reviewing messages to verify his alibi for the GBPD's

investigation. See Jimeno, 500 U.S. at 251. The GBPD officer's

report explained that Burch "consented to Lt. Allen and I [two

GBPD officers] looking at the text messages between him and

[Burch's acquaintance] last night and also indicated I could

take his phone to the department to have the information on it

downloaded." Burch's signed consent form is also specific to

the "City of Green Bay Police Department" and indicated that

Burch gave certain members of the GBPD permission to search his

phone. Critically absent from the report or the consent form is

any mention of any other law enforcement agency, the possibility
of the GBPD sharing the entirety of the downloaded data, or even

that Burch was consenting to the GBPD retaining indefinitely all

of his phone's information. Cf. Douglas, 123 Wis. 2d at 21-22.

7
 No. 2019AP1404-CR.rfd

¶74 Burch's consent was therefore limited to the GBPD for

the GBPD's investigation.3 See Terry, 392 U.S. at 25-26, 29

(requiring courts to interpret warrant exceptions as "confined

in scope" and "strictly circumscribed"). With respect to other

agencies and their investigations, Burch maintained a reasonable

expectation of privacy in the data downloaded by the GBPD but

unrelated to its investigation, including his internet search

history and Google email account. See Carpenter, 138 S. Ct.

at 2217 (holding that, because of cell phone data's "unique

nature," a person "maintains a legitimate expectation of

privacy" in the data even after consensually giving it to

another party for a limited purpose); Hughes, 958 N.W.2d at 111

(concluding that the lawful seizure and search of certain cell

phone information does not "extinguish[] that otherwise

reasonable expectation of privacy in the entirety" of that

information). Consequently, the Sheriff's Office's subsequent

review of Burch's data invaded Burch's reasonable expectation of

privacy such that it was a search under the Fourth Amendment.

2. The Sheriff's Office Acted Unreasonably in Searching the
GBPD's Download of Burch's Cell Phone Data.
¶75 The Sheriff's Office decided that no warrant was

required for its search after determining that Burch's consent

The circuit court's determination that Burch placed no
3

parameters on the scope of his consent is suspect given that his
conversation with the GBPD about his phone was strictly limited
to his text messages. The categorical uniqueness of private
cell phone data requires circuit courts to take seriously the
admonition that exceptions to the warrant requirement like
consent be interpreted as "confined in scope" and "strictly
circumscribed." See Riley v. California, 573 U.S. 373, 382, 393
(2014); Terry v. Ohio, 392 U.S. 1, 25-26, 29 (1968).

8
 No. 2019AP1404-CR.rfd

to the GBPD extended to the Sheriff's Office. But as discussed

above, Burch's "unequivocal and specific" consent extended only

to certain members of the GBPD, and only so they could review

his text messages to confirm his alibi. See Reed, 384

Wis. 2d 469, ¶8. Burch did not consent to all of the

information on his phone being available to other law

enforcement agencies for some later, unrelated investigation.

And the Sheriff's Office did not independently get Burch's

consent to search his cell phone information.

¶76 Given those facts, no reasonable person in Burch's

position would have understood that his consent to the GBPD was

an open invitation for any other law enforcement agency to

search his private information whenever it wanted to and without

a warrant. Therefore, the consent exception to the Fourth

Amendment's warrant requirement does not apply to the Sheriff's

Office's subsequent warrantless search of Burch's private cell

phone data for an unrelated investigation. That search was

unreasonable and violated the Fourth Amendment.

B. Evidence of Burch's Google Location Data and His Internet
Search History Should Be Suppressed.
¶77 Having concluded that the Sheriff's Office's search

violated the Fourth Amendment, the next question is whether the

exclusionary rule applies; that is, whether excluding, or

suppressing, the unlawfully obtained evidence would sufficiently

deter the same police conduct in the future. Here, Burch's

Google location data and his internet search history should be
excluded because if they are not, other law enforcement agencies

are likely to repeat the Sheriff's Office's unconstitutional

9
 No. 2019AP1404-CR.rfd

search of downloaded cell phone data, especially given the

ubiquity of cell phones and the increasing prevalence of

personal digital data in criminal investigations.

¶78 The exclusionary rule——that evidence obtained in

violation of the Fourth Amendment be excluded from trial——

ensures that the Fourth Amendment's right to be free from

unreasonable searches remains one "of substance rather than mere

tinsel." Hoyer v. State, 180 Wis. 407, 415, 193 N.W. 89 (1923).

By excluding otherwise relevant evidence, "[t]he exclusionary

rule generally serves to 'deter deliberate, reckless, or grossly

negligent conduct, or in some circumstances recurring or

systemic negligence.'" Blackman, 377 Wis. 2d 339, ¶68 (quoting

Herring v. United States, 555 U.S. 135, 150-51 (2009)). The

rule thus incentivizes "the law enforcement profession as a

whole" to conduct itself "in accord with the Fourth Amendment."

Gates, 462 U.S. at 261 n.15 (White, J., concurring in the

judgment).

¶79 Given that critical function, the United States
Supreme Court has permitted deviation from the exclusionary rule

only when the deterrent value of excluding the evidence is

"marginal" or "nonexistent" and outweighed by the social cost of

doing so. See, e.g., United States v. Leon, 468

U.S. 897, 913-17, 922 (1984). Such is the case when there is no

police misconduct to deter or when the police misconduct is

"isolated," "nonrecurring," and "attenuated." See id. at 922;

Herring, 555 U.S. at 137, 144. For example, excluding
unlawfully obtained evidence is inappropriate if the police

acted in objectively reasonable reliance on either a facially

10
 No. 2019AP1404-CR.rfd

valid warrant properly issued by a neutral, detached magistrate;

an apparently constitutional statute; or a binding appellate

precedent. See Leon, 468 U.S. 897 (warrants);4 Illinois v.

Krull, 480 U.S. 340 (1987) (statutes); Davis v. United

States, 564 U.S. 229, 239-41 (2011) (appellate precedents).

Likewise, exclusion is inappropriate when an arresting officer

acts in objectively reasonable reliance on either a judicial or

police employees' infrequent clerical mistake. See Arizona v.

Evans, 514 U.S. 1, 14-16 (1995) (court clerk made a

recordkeeping error regarding outstanding arrest warrants only

once "every three or four years"); Herring, 555 U.S. at 144-47

(police employees' clerical error in warrant database had never

happened before). The common thread through each of these cases

is that the fault lies with someone who is not directly engaged

in the "competitive enterprise of ferreting out crime"; who has

"no stake in the outcome of particular prosecutions." See

Evans, 514 U.S. at 15.

¶80 Conversely, the exclusionary rule applies when
evidence is unlawfully obtained due to an error made by law

enforcement. See Leon, 468 U.S. at 923. For instance, evidence

should be suppressed when law enforcement secures evidence based

on a facially deficient warrant, or when a warrant is issued

based on an officer knowingly or recklessly stating a falsehood

in the warrant affidavit. See id. The same goes for when

police exceed a valid warrant's authority when executing it.

See id. As for the police relying on statutory authority, the

See also Massachusetts v. Sheppard, 468 U.S. 981, 988-91
4

(1984).

11
 No. 2019AP1404-CR.rfd

exclusionary rule still applies when police officers

misinterpret and "act outside the scope" of a statute and when a

reasonable officer would have known either that the law in

question is unconstitutional or that the conduct authorized by

the statute violates other clearly established law. Krull, 480

U.S. at 355, 360 n.17. Indeed, the rule applies even to

unlawfully negligent police conduct when the conduct is

"recurring or systemic." E.g., Herring, 555 U.S. at 144.

¶81 The exclusionary rule applies in this case because it

was the Sheriff's Office's conduct that rendered unlawful its

search of Burch's cell phone, not some detached third party's.

There was no statute or judicial precedent condoning a

warrantless search of another agency's download of a person's

private cell phone data. Instead, the Sheriff's Office judged

for itself, incorrectly, that the Fourth Amendment's warrant

requirement did not apply to Burch's cell phone data. The

unlawful conduct here——not obtaining a warrant to search Burch's

private cell phone data——is solely attributable to the Sheriff's
Office's detectives. And because those detectives are directly

engaged in the "competitive enterprise of ferreting out crime,"

the exclusionary rule should apply. See Evans, 514 U.S. at 15.

¶82 Applying the rule is also justified because the record

demonstrates that warrantless searches of private cell phone

information are commonplace, and therefore likely to recur.

Officers from both the GBPD and the Sheriff's Office confirmed

that it is "very common" for agencies to share "full downloads"
of private cell phones with other agencies without first

obtaining a warrant, adding that their agencies "regularly" do

12
 No. 2019AP1404-CR.rfd

so. This widespread neglect of the Fourth Amendment's warrant

requirement is just the kind of "systemic negligence" the

exclusionary rule is designed to correct. See Herring, 555 U.S.

at 144. The exclusionary rule thus squarely applies here.

¶83 The State's counterarguments are unavailing. Its

contention that the Sheriff's Office reasonably relied upon its

own determination regarding the scope of Burch's consent misses

the point. It is not up to the police to determine the contours

of an exception to a constitutional requirement restricting

their own conduct. See Leon, 468 U.S. at 959 (Brennan, J.,

dissenting) (presciently lamenting that exceptions to the

exclusionary rule would not stay "confined" but instead be

wrongfully extended "to situations in which the police have

conducted a warrantless search solely on the basis of their own

judgment"). Moreover, because the police may encounter

circumstances that are on the margins of the law regarding

warrant exceptions——as is the case here——police officers are

required to "err on the side of constitutional behavior" and get
a warrant.5 See United States v. Johnson, 457 U.S. 537, 561

The State erroneously argues that the Sheriff's Office's
5

search is akin to law enforcement's ability to take a "second
look" at physical evidence inventoried during a jail intake or
that it already lawfully seized. See State v. Betterley, 191
Wis. 2d 406, 418, 529 N.W.2d 216 (1995); State v. Riedel, 2003
WI App 18, ¶16, 259 Wis. 2d 921, 656 N.W.2d 789. But as the
United States Supreme Court explained in Riley, "cell phones, as
a category, implicate privacy concerns far beyond those
implicated" by physical objects. 573 U.S. at 393. And because
a "search of the information on a cell phone bears little
resemblance" to other types of searches, the rationales for
other searches do not extend to cell phone information. See id.
at 386. Therefore, the State's arguments fail. See People v.
Hughes, 958 N.W.2d 98, 111-15 (Mich. 2020).

13
 No. 2019AP1404-CR.rfd

(1982); Blackman, 377 Wis. 2d 339, ¶53 (warrantless searches

executed outside any "clearly delineated" warrant exception are

"per se unreasonable" and "unlawful"). The Sheriff's Office's

erroneous determination that Burch's consent extended to the

Sheriff's Office is no justification for failing to get a

warrant.

¶84 Nor is the Sheriff's Office relieved of its Fourth

Amendment duty to get a warrant simply because law enforcement

agencies "regularly" share this type of information. The

pervasiveness of this practice is no defense to the exclusionary

rule; it is the reason to apply it. See Herring, 555 U.S.

at 144 (exclusion applies when unreasonable police conduct is

"recurring" or "systemic"). The same goes for the majority's

characterization of the Sheriff's Office's conduct as "by the

book." Majority op., ¶22. If following "the book" leads to

violations of the Fourth Amendment, then the exclusionary rule's

deterrent value is at its peak. Excluding evidence obtained by

following such an unlawful and widespread policy provides
significant societal value by both specifically deterring

continued adherence to an unconstitutional practice and more

broadly incentivizing police agencies to adopt policies in line

with the Fourth Amendment.6 See Wayne R. LaFave, 1 Search &

Seizure § 1.3(i) (6th ed. 2020). This is especially true when

6 The State counters that because the Sheriff's Office may
have had access to Burch's Google email account and internet
search history via a lawful, independent source, that evidence
should not be excluded. See State v. Carroll, 2010
WI 8, ¶¶44-45, 322 Wis. 2d 299, 778 N.W.2d 1. But the State has
forfeited that argument by failing to raise it below. See State
v. Counihan, 2020 WI 12, ¶25, 390 Wis. 2d 172, 938 N.W.2d 530.

14
 No. 2019AP1404-CR.rfd

the Constitution already provides law enforcement with a simple

solution for how to lawfully obtain cell phone data: get a

warrant. See Riley, 573 U.S. at 403.

C. The Majority Opinion Has No Support in Fourth Amendment
Jurisprudence.
¶85 The majority opinion offers a contrary analysis that

ignores the novel constitutional problems presented by cell

phone data, is inconsistent with the Fourth Amendment's text,

and undermines the exclusionary remedy.

¶86 The majority opinion's analysis reveals a lack of

appreciation for the fundamental differences between digital

cell phone data and more "traditional," non-digital evidence

that law enforcement might share with other agencies. The

Fourth Amendment treats cell phone data differently because it

often contains nearly all the "privacies of [a person's] life,"

such that "any extension" of Fourth Amendment principles "to

digital data has to rest on its own bottom." See Riley, 573

U.S. at 393, 403 (quoting another source); Carpenter, 138 S. Ct.

at 2219 (explaining that Fourth Amendment jurisprudence must

account for the "seismic shifts in digital technology").

Accordingly, it is a grave analytical error to "mechanically

apply[]" to cell phone data Fourth Amendment rationales that

were developed without such invasive technologies in mind.

Carpenter, 138 S. Ct. at 2219; see also Riley, 573 U.S.

at 400-01 (rejecting the argument that the police can search

cell phone data under the same rationale that allows them to
obtain "the same information from a pre-digital counterpart").

Or, as the United States Supreme Court put it, treating cell

15
 No. 2019AP1404-CR.rfd

phone data the same as its non-digital analogues "is like saying

a ride on horseback is materially indistinguishable from a

flight to the moon. Both are ways of getting from point A to

point B, but little else justifies lumping them together."

Riley, 573 U.S. at 393. The majority opinion, however, is

content to toss a saddle on a spaceship and call it a horse.

Nowhere does the majority opinion account for Burch's special

privacy interest in his cell phone data, leaving a tremendous

hole in its exclusionary rule analysis.

¶87 More troubling is the majority's disregard for the

Fourth Amendment's text. It is bedrock Fourth Amendment law

that search warrants are generally required and that a search

without a warrant is per se unlawful. See, e.g., City of

Ontario v. Quon, 560 U.S. 746, 760 (2010); Blackman, 377

Wis. 2d 339, ¶53. The majority's assertion that "there is

nothing concerning under current Fourth Amendment doctrine with

how the Sheriff's Office detectives conducted themselves"

shockingly discards this well-settled principle. Indeed, the
majority opinion fails to even mention the presumption that

warrantless searches violate the Fourth Amendment.

¶88 But worse than mere silence, the majority's refusal to

apply the exclusionary rule flips this presumption on its head.

According to the majority, if "no case from this court or the

federal courts" directs the police to get a warrant, then the

police act "reasonably" in not getting a warrant. Majority

op., ¶23. The majority appears to create a new prerequisite for
applying the exclusionary rule, holding that it applies only if

a court has previously declared that the police conduct at issue

16
 No. 2019AP1404-CR.rfd

is unconstitutional. Imposing this hurdle undermines the

exclusionary remedy for Fourth Amendment violations and is

directly contrary to both our and the United States Supreme

Court's Fourth Amendment jurisprudence.

¶89 All of which makes inexcusable the majority opinion's

refusal to address the constitutionality of the Sheriff's

Office's search. Despite law enforcement's admittedly "very

common" practice of sharing with other agencies entire downloads

of private cell phone data, that recurring Fourth Amendment

violation will continue with impunity unless and until the court

engages with the specific Fourth Amendment issue raised by

private cell phone information. By skipping straight to whether

the exclusionary rule applies, the majority opinion deprives

aggrieved defendants——and future courts——of the very prior

precedent now necessary to remedy law enforcement's continued

unconstitutional conduct:

Forgoing a knotty constitutional inquiry makes for
easier sledding, no doubt. But the inexorable result
is "constitutional stagnation"——fewer courts
establishing law at all, much less clearly doing
so, . . . [creating a] Catch-22. [Defendants] must
produce precedent even as fewer courts are producing
precedent. Important constitutional questions go
unanswered precisely because no one's answered them
before. Courts then rely on that judicial silence to
conclude there's no equivalent case law on the
books. . . . If courts leapfrog the underlying
constitutional merits in cases raising novel issues
like digital privacy, then constitutional clarity——
matter-of-fact guidance about what the Constitution
requires——remains exasperatingly elusive.
Result: gauzy constitutional guardrails as
technological innovation outpaces legal adaptation.
Zadeh v. Robinson, 928 F.3d 457, 479-80 (5th Cir. 2019)

(Willet, J., concurring), cert. denied, 141 S. Ct. 110 (2020).
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 No. 2019AP1404-CR.rfd

Together with its new prior-precedent requirement, the majority

opinion's avoidance of the Fourth Amendment issues here

perpetuates a cycle of diminished police accountability and

courts' unwillingness to address it.

¶90 Given that the Fourth Amendment law specific to cell

phone data is undeveloped, this court should be providing "clear

guidance to law enforcement through categorical rules."

Riley, 573 U.S. at 398; see also Michigan v. Summers, 452

U.S. 692, 705 n.19 (1981) (explaining that clear "workable"

rules are necessary so that difficult Fourth Amendment questions

are not resolved in an "ad hoc, case-by-case fashion by

individual police officers") (quoting another source)). If a

law enforcement agency wishes to search a person's private

information, such as cell phone data, and the person did not

consent to that agency's search, the agency must get a warrant.

III. CONCLUSION

¶91 The Sheriff's Office should have obtained a warrant to

search Burch's private cell phone data. Because it did not, the
evidence it found as a result of that search should be

suppressed. The majority's refusal to apply the exclusionary

rule is incompatible with our Fourth Amendment jurisprudence and

perverts the long-standing bedrock requirement that police

obtain a warrant to search private information. I therefore

respectfully dissent from that part of the majority opinion.

¶92 I am authorized to state that Justice JILL J. KAROFSKY
joins this opinion and that Justice ANN WALSH BRADLEY joins this

opinion except for footnote 1.

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 No. 2019AP1404-CR.awb

¶93 ANN WALSH BRADLEY, J. (dissenting). Ubiquitous use

does not mean the average wearer of a Fitbit knows how it works.

Nor does ubiquitous use indicate reliability sufficient to be

admissible in a court of law.

¶94 An average jury member would likely know what a Fitbit

is and what it does. Of course, as relevant here, it counts the

wearer's steps. But that isn't the question. In determining

whether expert testimony is required, the relevant inquiry is

how a Fitbit counts the wearer's steps and then ultimately,

whether it does so with sufficient reliability.

¶95 How does it work? A Fitbit device uses a

microelectronic triaxial accelerometer to capture a person's

body motion in three-dimensional space and record related data.

This motion data is then analyzed by utilizing proprietary

algorithms to surmise patterns and thus to identify daily steps

taken.

¶96 Is it sufficiently reliable to be admitted as evidence

in court? I don't know. But, I do know that the answer does
not lie in its ubiquitous use.

¶97 I also know that absent expert testimony there is

insufficient foundation in this record for the majority to

determine, in essence, that a presumption of accuracy and

reliability attends the underlying technology of a Fitbit. The

error of such a presumption is made manifest by reference to an

overarching analysis of 67 studies on Fitbit accuracy

disseminated by the National Center for Biotechnology
Information (NCBI), under the auspices of the U.S. National

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Institutes of Health (NIH). The researchers found that Fitbit

devices were "likely to meet acceptable accuracy for step count

approximately half the time." Lynne M. Feehan, et al., Accuracy

of Fitbit Devices: Systematic Review and Narrative Syntheses of

Quantitative Data,

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6107736/ (2018).

¶98 In citing this study, I neither endorse nor disclaim

its conclusions. It suggests, however, when a compilation of

studies indicates acceptable accuracy is met only "half the

time," that something may be amiss with the majority's

presumption of accuracy and reliability.

¶99 Expert testimony is required when matters are

presented that are "unusually complex." White v. Leeder, 149

Wis. 2d 948, 960, 440 N.W.2d 557 (1989). Movement measured by a

"microelectronic triaxial accelerometer" and analyzed by

proprietary algorithms certainly fits that bill.

¶100 In my view, the technology underlying a Fitbit is not

within the ordinary experience of an average jury member.
Fitbits and other wearable devices may be ubiquitous, but it

does not follow from this premise that the technology underlying

their use is not "unusually complex."

¶101 Expert testimony assists the trier of fact to

understand the evidence and to determine a fact in issue. The

accuracy of the number of steps recorded on Douglass Detrie's

Fitbit is certainly a fact in issue. Thus, expert testimony

should have been required to assist the jury in understanding
the technology and assessing its reliability.

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¶102 Invoking a deferential standard, it is not unusual for

an appellate court to do only a cursory analysis of an

evidentiary issue. But this is not the usual case and a more

nuanced analysis is required.

¶103 This case presents a groundbreaking question. To my

knowledge, this is the first appellate court decision in the

country to conclude that Fitbit step-counting evidence is

admissible absent expert testimony explaining how the device

works. The parties have not cited, and I have not found, any

case making such a proclamation. The majority's analysis

provides a slim reed upon which to support such a novel

determination.

¶104 Rather than allowing evaluation of the question, the

majority cuts off the debate. It essentially rubber stamps the

circuit court's erroneous analysis and declares Fitbit's

technology to be simple enough to be presented as evidence

without the benefit of an expert witness or further

consideration of its reliability.
¶105 Although I join Justice Dallet's dissent, concluding

that the search of Burch's cell phone at issue violated his

Fourth Amendment rights and that the good faith exception to the

warrant requirement does not apply, I do not join footnote 1

that concurs with the majority's analysis of the Fitbit

evidence. Because I conclude that the circuit court erroneously

admitted the Fitbit evidence without an expert witness to

establish the reliability of the science underlying the Fitbit
technology, I respectfully dissent.

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I

¶106 I briefly recount the facts that are relevant to the

issue on which I write: the admission of the Fitbit evidence.

¶107 As the majority opinion sets forth, the initial

suspect in the crime at issue here was Douglass Detrie, the

victim's boyfriend. Majority op., ¶4. However, the

investigation shifted after police learned that Detrie's Fitbit

device had recorded only 12 steps during the time the homicide

was committed. Burch was ultimately arrested and charged.

¶108 The State sought to present evidence regarding

Detrie's Fitbit, and Burch moved to exclude it. Id., ¶11. As

relevant here, Burch contended that the State must present

expert testimony to establish the reliability of the science

behind the Fitbit device. Id.1

¶109 The circuit court granted Burch's motion in part and

denied it in part. Specifically, the circuit court excluded

Fitbit evidence related to sleep monitoring, but it allowed the

admission of the step-counting data without the testimony of an
expert regarding the science underlying the Fitbit technology.

Id., ¶11 & n.3.

¶110 In the circuit court's estimation, a Fitbit is more

akin to an electronic monitoring device (which does not require

expert testimony, see State v. Kandutsch, 2011 WI 78, 336

1 Burch made several additional arguments, including an
assertion that Fitbit's records were not properly authenticated,
which he renews on appeal. Because I determine that expert
testimony was necessary to admit the evidence in question, I do
not reach Burch's arguments regarding authentication.

4
 No. 2019AP1404-CR.awb

Wis. 2d 478, 799 N.W.2d 865) than to a preliminary breath test

(which requires expert testimony, see State v. Doerr, 229

Wis. 2d 616, 599 N.W.2d 897 (Ct. App. 1999)). Similarly, the

circuit court distinguished Fitbit data from DNA, fingerprint

analysis, blood alcohol content tests, tool mark evidence and

accident reconstruction because "few people encounter those

things in their everyday life."

¶111 Comparing a Fitbit to an electronic monitoring device,

the circuit court stated that a Fitbit is "passively worn by a

person," and the device collects data "based on that person's

movements, which is then transmitted and recorded. There is no

active manipulation by the wearer to achieve the results; the

results are simply a record of the wearer's movements, i.e.,

their location or the number of steps they took." Thus, in the

circuit court's view "the step-counting feature of the Fitbit

Flex, like the [electronic monitoring device], is not so

unusually complex or esoteric that the jury will require the aid

of expert testimony to interpret the information."
¶112 At trial, because it was not required to provide an

expert to introduce the data from Detrie's Fitbit, the State

relied upon the testimony of Tyler Behling, a computer forensic

crime analyst with the Brown County Sheriff's Office. Although

Behling claimed to have knowledge of how a Fitbit works "on a

high level," he did not know the answer when asked how a Fitbit

and a Bluetooth device send information from one to the other,

how Fitbit stores its data, whether Fitbit data can be edited,

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whether the device would register steps while it is not being

worn, or what a Fitbit's error rate is.

¶113 Despite the dearth of technical testimony regarding

how a Fitbit actually works, the majority now affirms the

circuit court's determination. It concludes that "[g]iven the

widespread availability of Fitbits and other similar wireless

step-counting devices in today's consumer marketplace, the

circuit court reasonably concluded Detrie's Fitbit was not so

'unusually complex or esoteric' that the jury needed an expert

to understand it." Majority op., ¶31.

II

¶114 It has long been the law that expert testimony is

required when a matter involves "special knowledge or skill or

experience on subjects which are not within the realm of the

ordinary experience of mankind, and which require special

learning, study and experience." Cramer v. Theda Clark Mem'l

Hosp., 45 Wis. 2d 147, 150, 172 N.W.2d 427 (1969). "The

requirement of expert testimony is an extraordinary one," and
should be applied "only when unusually complex or esoteric

issues are before the jury." White, 149 Wis. 2d at 960.

¶115 "In considering what constitutes the 'ordinary

experience of mankind'——i.e. the average juror——courts have not

tailored this standard to the lowest common denominator.

Rather, courts attempt to evaluate, on a case-by-case basis,

whether expert testimony is required because the issue is

outside the realm of lay comprehension." Kandutsch, 336
Wis. 2d 478, ¶29.

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¶116 The circuit court here determined that the technology

underlying a Fitbit is not outside the realm of lay

comprehension. It compared a Fitbit to a watch in that "the

public generally understands the principle of how it functions

and accepts its reliability without knowing the exact mechanics

of its internal workings." Further, it determined that a Fitbit

is not subject to "active manipulation by the wearer to achieve

the results; the results are simply a record of the wearer's

movements, i.e., their location or the number of steps they

took."

¶117 But the expert testimony standards do not rest on

ubiquity. Instead, they rest on the complexity of the subject

matter. Although many members of the jury may have been wearing

Fitbits or similar devices, such a fact would not inform the

question of whether those jury members understand how a Fitbit

works or whether the technology is reliable.

¶118 What does the average person really know about how a

Fitbit works, much less its reliability? As one study described
it, "Fitbit devices use a microelectronic triaxial accelerometer

to capture body motion in 3-dimensional space, with these motion

data analyzed using proprietary algorithms to identify patterns

of motion to identify daily steps taken, energy expenditure,

sleep, distance covered, and time spent in different intensity

of activities." Feehan, et al., supra. According to the

majority, the average juror would understand, without expert

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testimony, not only what a "microelectronic triaxial

accelerometer" is, but how it works. Really?2

¶119 If the State had presented an expert, that expert

would have had to meet the requirements for expert testimony

established by the United States Supreme Court in Daubert.3

Pursuant to the Daubert standard, as codified in Wis. Stat.

§ 907.02(1),4 the circuit court must act as a gatekeeper and make

a threshold determination that the testimony is reliable in

order for it to be presented at trial. State v. Dobbs, 2020 WI

64, ¶43, 392 Wis. 2d 505, 945 N.W.2d 609. By not requiring the

State to present an expert, the circuit court and the majority

allow the State to skirt this initial reliability determination.

¶120 There are various ways in which threshold reliability

can be demonstrated. See 7 Daniel D. Blinka, Wisconsin Practice

Series: Wisconsin Evidence § 702.402 (4th ed. 2020). There may

2Further, the intricacies of Fitbit's technology are
"proprietary," setting up an additional roadblock to the jury's
full knowledge and full understanding of how the device works.
See State v. Loomis, 2016 WI 68, ¶66, 371 Wis. 2d 235, 881
N.W.2d 749 (explaining that "proprietary nature" has been
invoked to prevent disclosure of certain information).
3 Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579 (1993).
4 Wisconsin Stat. § 907.02(1) provides:

If scientific, technical, or other specialized
knowledge will assist the trier of fact to understand
the evidence or to determine a fact in issue, a
witness qualified as an expert by knowledge, skill,
experience, training, or education, may testify
thereto in the form of an opinion or otherwise, if the
testimony is based upon sufficient facts or data, the
testimony is the product of reliable principles and
methods, and the witness has applied the principles
and methods reliably to the facts of the case.

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 No. 2019AP1404-CR.awb

be a statute indicating that certain tests or methods are

admissible. See, e.g., Wis. Stat. § 885.235 (addressing

chemical tests for intoxication). There is no statute

addressing Fitbit evidence.

¶121 We can also look to court precedent which has already

determined certain principles to be reliable. See, e.g., State

v. Hanson, 85 Wis. 2d 233, 244, 270 N.W.2d 212 (1978)

(discussing the reliability of the underlying principles of

speed radar detection that employs the Doppler effect). The

reliability of Fitbit's step counting capability is a novel

issue, so there is no precedent on point.

¶122 Stipulations or judicial notice may also be

appropriate when a fact is "capable of accurate and ready

determination by resort to sources whose accuracy cannot

reasonably be questioned." Wis. Stat. § 902.01(2)(b). Again,

these do not fit the present scenario——the reason we are here is

because the parties do not agree and Burch reasonably questions

the accuracy of Fitbit's step count.
¶123 Finally, if none of the above proves to be an

acceptable avenue to demonstrate the accuracy and reliability of

the scientific principles sufficient to be accorded a prima

facie presumption, expert testimony is necessary to explain the

underlying scientific principles and to demonstrate their

reliability. Here, no expert was presented.

¶124 The evidentiary process requires that the scientific

principles be presented to the court before the evidence is
determined to be reliable. In a court of law, process matters.

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Without fulfilling one of these avenues, the threshold

reliability determination cannot be made.

¶125 And what of Fitbit's reliability? Such reliability

can depend on a number of factors, such as whether the user has

self-manipulated the data, if the Fitbit is temporarily removed,

where on the body the device is worn, or the type of physical

activity in which the wearer is engaged. Feehan, et al., supra;

Katherine E. Vinez, The Admissibility of Data Collected from

Wearable Devices, 4 Stetson J. Advoc. & L. 1, 16 (2017). In a

comprehensive aggregation of 67 different studies, researchers

found that "[c]onsistent evidence indicated that Fitbit devices

were likely to meet acceptable accuracy for step count

approximately half the time." Feehan, et al., supra. Yet in

the view of the majority and of the circuit court, an expert is

not necessary to establish the reliability of Detrie's step

count——the Fitbit evidence can go before the jury with no

technical or scientific explanation.

¶126 Indeed, questions arise about the reliability of
wearable devices despite their widespread acceptance. See

Vinez, supra, at 16. If reliability questions exist, where

better than the circuit court to present the case for and

against such reliability? Instead of remanding to the circuit

court for evaluation of the question, the majority curtly

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declares Fitbit's technology to be simple enough to be put

before a jury without the benefit of an expert.5

¶127 When new and popular devices emerge, courts should be

wary of blindly accepting the data they produce without a

thorough examination of the underlying technology. "Machines

warrant no blind faith, and whatever trust they receive must be

earned through the crucible of the rules of evidence." Brian

Sites, Machines Ascendant: Robots and the Rules of Evidence, 3

Geo. L. Tech. Rev. 1, 1-2 (2018). In many cases, such an

examination will require an expert. In my view, this is such a

case.

¶128 Rather than break new ground as does the majority, I

would proceed with caution. Basing the necessity of expert

testimony on ubiquity rather than complexity sets a dangerous

path.

¶129 For the foregoing reasons, I respectfully dissent.

See Nicole Chauriye, Wearable Devices as Admissible
5

Evidence: Technology is Killing our Opportunities to Lie, 24
Cath. U. J. L. & Tech. 495, 517 (2016) (arguing that "the trier
of fact would greatly benefit from mandated expert testimony to
explain the accuracy and details of the data recorded by the
wearable technology").

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1