LEGALITY OF INTRUSION-DETECTION SYSTEM TO PROTECT
UNCLASSIFIED COMPUTER NETWORKS IN THE EXECUTIVE BRANCH
Operation of the EINSTEIN 2.0 intrusion-detection system complies with the Fourth Amendment
to the Constitution, title III of the Omnibus Crime Control and Safe Streets Act of 1968, the Foreign
Intelligence Surveillance Act, the Stored Communications Act, and the pen register and trap and trace
provisions of chapter 206 of title 18, United States Code, provided that certain log-on banners or
computer-user agreements are consistently adopted, implemented, and enforced by executive departments
and agencies using the system. Operation of the EINSTEIN 2.0 system also does not run afoul of state
wiretapping or communications privacy laws.
August 14, 2009
MEMORANDUM OPINION FOR AN
ASSOCIATE DEPUTY ATTORNEY GENERAL
This memorandum briefly summarizes the current views of the Office of Legal Counsel
on the legality of the EINSTEIN 2.0 intrusion-detection system. This Office previously
considered the legality of the system in an opinion of January 9, 2009. See Memorandum for
Fred F. Fielding, Counsel to the President, from Steven G. Bradbury, Principal Deputy Assistant
Attorney General, Office of Legal Counsel, Re: Legal Issues Relating to the Testing, Use, and
Deployment of an Intrusion-Detection System (EINSTEIN 2.0) to Protect Unclassified Computer
Networks in the Executive Branch (Jan. 9, 2009) (“EINSTEIN 2.0 Opinion”). We have reviewed
that opinion and agree that the operation of the EINSTEIN 2.0 program complies with the Fourth
Amendment to the United States Constitution, title III of the Omnibus Crime Control and Safe
Streets Act of 1968, Pub. L. No. 90-351, 82 Stat. 211, 18 U.S.C. § 2510 et seq. (2006), as
amended (“the Wiretap Act”), the Foreign Intelligence Surveillance Act, Pub. L. No. 95-511, 92
Stat. 1783, 50 U.S.C. § 1801 et seq. (West Supp. 2009), as amended (“FISA”), the Stored
Communications Act, Pub. L. No. 99-508, tit. II, 100 Stat. 1848 (1986), 18 U.S.C. § 2701(a)(1)
(2006), as amended, and the pen register and trap and trace provision of title 18, United States
Code, 18 U.S.C. § 3121 et seq. (2006), as amended. Accordingly, we have drawn upon the
analysis in that opinion in preparing this summary, supplementing that material with analysis of
an additional legal issue.
We have assumed for purposes of our analysis that computer users generally have a
legitimate expectation of privacy in the content of Internet communications (such as an e-mail)
while it is in transmission over the Internet. 1 See, e.g., United States v. Lifshitz, 369 F.3d 173,
190 (2d Cir. 2004) (analogizing expectation of email user in privacy of email to expectation of
individuals communicating by regular mail); United States v. Maxwell, 45 M.J. 406, 418
(C.A.A.F. 1996) (sender of an email generally “enjoys a reasonable expectation that police
officials will not intercept the transmission without probable cause and a search warrant”); see
1
Computer users do not have an objectively reasonable expectation of privacy in addressing and routing
information conveyed for the purpose of transmitting Internet communications to or from a user. See Quon v. Arch
Wireless Operating Co., Inc., 529 F.3d 892, 904-05 (9th Cir. 2008); United States v. Forrester, 512 F.3d 500, 510-
11 (9th Cir. 2008); cf. Smith v. Maryland, 442 U.S. 735, 743-44 (1979) (no legitimate expectation of privacy in
dialing, routing, addressing, and signaling information transmitted to telephone companies).
Opinions of the Office of Legal Counsel in Volume 33
also Quon, 529 F.3d at 905 (“[U]sers do have a reasonable expectation of privacy in the content
of their text messages vis-a-vis the service provider.”). Even given this assumption, however, we
believe the deployment, testing, and use of EINSTEIN 2.0 technology complies with the Fourth
Amendment where each agency participating in the program consistently adopts, implements,
and enforces the model log-on banner or model computer-user agreements described in this
Office’s prior opinion, or their substantial equivalents. See EINSTEIN 2.0 Opinion at 5-6.
First, we conclude that the adoption, implementation, and enforcement of model log-on
banners or model computer-user agreements eliminates federal employees’ reasonable
expectation of privacy in their uses of Government-owned information systems with respect to
the lawful government purpose of protecting federal systems against network intrusions and
exploitations. We therefore do not believe that the operation of intrusion-detection sensors as
part of the EINSTEIN 2.0 program constitutes a “search” for Fourth Amendment purposes. See
Minnesota v. Carter, 525 U.S. 83, 88 (1998). Whether a Government employee has a legitimate
expectation of privacy in his use of governmental property at work in particular circumstances is
determined by “[t]he operational realities of the workplace,” and “by virtue of actual office
practices and procedures, or by legitimate regulation.” O’Connor v. Ortega, 480 U.S. 709, 717
(1987) (plurality); see United States v. Simons, 206 F.3d 392, 398 (4th Cir. 2000) (“[O]ffice
practices, procedures, or regulations may reduce legitimate privacy expectations.”). The
existence of an expectation of privacy, moreover, may depend on the nature of the intrusion at
issue. See O’Connor, 480 U.S. at 717-18 (plurality) (suggesting that a government employee’s
expectation of privacy might be unreasonable “when an intrusion is by a supervisor” but
reasonable when the intrusion is by a law enforcement official). The model banner and model
computer-user agreement discussed in our prior opinion are at least as robust as—and we think
stronger than—similar materials that courts have held eliminated a legitimate government
employee expectation of privacy in the content of Internet communications sent over government
systems. See, e.g., Simons, 206 F.3d at 398 (finding no legitimate expectation of privacy in light
of computer-use policy expressly noting that government agency would “‘audit, inspect, and/or
monitor’” employees’ use of the Internet, “including all file transfers, all websites visited, and
all e-mail messages, ‘as deemed appropriate’”) (quoting policy); United States v. Angevine, 281
F.3d 1130, 1132-33 (10th Cir. 2002) (finding no legitimate expectation of privacy in light of
computer-use policy stating that university “‘reserves the right to view or scan any file or
software stored on the computer or passing through the network, and will do so periodically’”
and has “‘a right of access to the contents of stored computing information at any time for any
purpose which it has a legitimate need to know’”) (quoting policy); United States v. Thorn, 375
F.3d 679, 682 (8th Cir. 2004), vacated on other grounds, 543 U.S. 1112 (2005) (finding no
legitimate expectation of privacy in light of computer-use policy warning that employees “‘do
not have any personal privacy rights regarding their use of [the employing agency’s] information
systems and technology,’” and that “‘[a]n employee’s use of [the agency’s] information systems
and technology indicates that the employee understands and consents to [the agency’s] right to
inspect and audit all such use as described in this policy’”) (quoting policy). We therefore
believe that the adoption, implementation, and enforcement of the language in those model
materials, or their substantial equivalents, by agencies participating in the EINSTEIN 2.0
program will eliminate federal employees’ legitimate expectations of privacy in their uses of
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Legality of Intrusion-Detection System to Protect Unclassified Computer Networks
in the Executive Branch
Government-owned information systems with respect to the lawful government purpose of
protecting federal systems against network intrusions and exploitations. 2
We also believe that individuals in the private sector who communicate directly with
federal employees of agencies participating in the EINSTEIN 2.0 program through Government-
owned information systems do not have a legitimate expectation of privacy in the content of
those communications provided that model log-on banners or agreements are adopted and
implemented by the agency. The Supreme Court has repeatedly held that where a person
“reveals private information to another, he assumes the risk that his confidant will reveal that
information to the authorities, and if that occurs the Fourth Amendment does not prohibit
governmental use of that information.” United States v. Jacobsen, 466 U.S. 109, 117 (1984); see
also United States v. Miller, 425 U.S. 435, 443 (1976) (“[T]he Fourth Amendment does not
prohibit the obtaining of information revealed to a third party and conveyed by him to
Government authorities, even if the information is revealed on the assumption that it will be used
only for a limited purpose and the confidence placed in the third party will not be betrayed.”);
SEC v. Jerry T. O’Brien, Inc., 467 U.S. 735, 743 (1984) (“[W]hen a person communicates
information to a third party even on the understanding that the communication is confidential, he
cannot object if the third party conveys that information or records thereof to law enforcement
authorities.”); Smith, 442 U.S. at 743-44 (“[A] person has no legitimate expectation of privacy in
information he voluntarily turns over to third parties.”). We believe this principle also applies to
a person who emails a federal employee at the employee’s personal email account when that
employee accesses his or her personal email account through a Government-owned information
system, when the consent procedures described above are followed. By clicking through the
model log-on banner or agreeing to the terms of the model computer-user agreement, a federal
employee gives ex ante permission to the Government to intercept, monitor, and search “any
communications” and “any data” transiting or stored on a Government-owned information
system for any “lawful purpose,” including the purpose of protecting federal computer systems
against malicious network activity. Therefore, an individual who communicates with a federal
employee who has agreed to permit the Government to intercept, monitor, and search any
personal use of the employee’s Government-owned information systems has no Fourth
Amendment right against the Government activity of protecting federal computer systems
against malicious network activity, as the employee has consented to that activity. See Jerry T.
O’Brien, Inc., 467 U.S. at 743; Jacobsen, 466 U.S. at 117; Miller, 425 U.S. at 443.
Under Supreme Court precedent, this principle applies even where, for example, the
sender of an email to an employee’s personal, Web-based email account (such as Gmail or
Hotmail) does not know of the recipient’s status as a federal employee or does not anticipate that
the employee might read, on a federal Government system, an email sent to a personal email
account at work or that the employee has agreed to Government monitoring of his
communications on that system. A person communicating with another assumes the risk that the
person has agreed to permit the Government to monitor the contents of that communication. See,
2
The use of log-on banners or computer-user agreements may not be sufficient to eliminate an employee’s
legitimate expectation of privacy if the statements and actions of agency officials contradict these materials. See
Quon, 529 F.3d at 906-07. Management officials of agencies participating in the EINSTEIN 2.0 program therefore
should ensure that agency practices are consistent with the statements in the model materials.
3
Opinions of the Office of Legal Counsel in Volume 33
e.g., United States v. White, 401 U.S. 745, 749-51 (1971) (plurality opinion) (no Fourth
Amendment protection against government monitoring of communications through transmitter
worn by undercover operative); Hoffa v. United States, 385 U.S. 293, 300-03 (1966)
(information disclosed to individual who turns out to be a government informant is not protected
by the Fourth Amendment); Lopez v. United States, 373 U.S. 427, 439 (1963) (same); cf.
Rathbun v. United States, 355 U.S. 107, 111 (1957) (“Each party to a telephone conversation
takes the risk that the other party may have an extension telephone and may allow another to
overhear the conversation. When such takes place there has been no violation of any privacy of
which the parties may complain.”). Accordingly, when an employee agrees to let the
Government intercept, monitor, and search any communication or data sent, received, or stored
by a Government-owned information system, the Government’s interception of the employee’s
Internet communications with individuals outside of the relevant agency through a Government-
owned information system does not infringe upon any legitimate expectation of privacy of the
parties to that communication.
We also think that, under the Court’s precedents, an individual who submits information
through the Internet to a federal agency participating in the EINSTEIN 2.0 program does not
have a legitimate expectation of privacy for Fourth Amendment purposes in the contents of the
information that he transmits directly to the participating agency. An individual has no
expectation of privacy in communications he makes to a known representative of the
Government. See United States v. Caceres, 440 U.S. 741, 750-51 (1979) (individual has no
reasonable expectation of privacy in communications with IRS agent made in the course of an
audit). Further, as just discussed, an individual who communicates information to another
individual who turns out to be an undercover agent of the Government has no legitimate
expectation of privacy in the content of that information. It follows a fortiori that where an
individual is communicating directly with a declared agent of the Government, the individual
does not have a legitimate expectation that his communication would not be monitored or
acquired by the Government.
Second, even if EINSTEIN 2.0 operations were to constitute a “search” under the Fourth
Amendment, we believe that those operations would be consistent with the Amendment’s
“central requirement” that all searches be reasonable. Illinois v. McArthur, 531 U.S. 326, 330
(2001) (internal quotation marks omitted). As discussed in the prior opinion of this Office, the
Government has a lawful, work-related purpose for the use of EINSTEIN 2.0’s intrusion-
detection system that brings the EINSTEIN 2.0 program within the “special needs” exception to
the Fourth Amendment’s warrant and probable cause requirements. See O’Connor, 480 U.S. at
720 (plurality); see also Nat’l Treasury Employees Union v. Von Raab, 489 U.S. 656, 665-66
(1989) (warrant and probable cause provisions of the Fourth Amendment are inapplicable to a
search that “serves special governmental needs, beyond the normal need for law enforcement”);
Griffin v. Wisconsin, 483 U.S. 868, 872-73 (1987) (special needs doctrine applies in
circumstances that make the “warrant and probable cause requirement impracticable”); United
States v. Heckenkamp, 482 F.3d 1142, 1148 (9th Cir. 2007) (preventing misuse of and damage to
university computer network is a lawful purpose). And, based upon the information available to
us, and as discussed in the prior opinion of this Office, we believe that the operation of the
EINSTEIN 2.0 program falls under that exception and is reasonable under the totality of the
circumstances. See United States v. Knights, 534 U.S. 112, 118-19 (2001) (reasonableness of a
4
Legality of Intrusion-Detection System to Protect Unclassified Computer Networks
in the Executive Branch
search under the Fourth Amendment is measured in light of the “totality of the circumstances,”
balancing “on the one hand, the degree to which it intrudes upon an individual’s privacy and, on
the other, the degree to which it is needed for the promotion of legitimate governmental
interests”) (internal quotation marks omitted; New Jersey v. T.L.O., 469 U.S. 325, 337 (1985)
(“what is reasonable depends on the context within which a search takes place”); O’Connor, 480
U.S. at 726 (plurality) (reasonable workplace search must be “justified at its inception” and
“reasonably related in scope to the circumstances which justified the interference in the first
place”) (internal quotation marks omitted). In light of that conclusion, we also think that a
federal employee’s agreement to the terms of the model log-on banner or the model computer-
user agreement, or those of a banner of user agreement that are substantially equivalent to those
models, constitutes valid, voluntary consent to the reasonable scope of EINSTEIN 2.0
operations. See Schneckloth v. Bustamonte, 412 U.S. 218, 219 (1973) (consent is “one of the
specifically established exceptions to the requirements of both a warrant and probable cause”);
United States v. Sihler, 562 F.2d 349 (5th Cir. 1977) (prison employee’s consent to routine
search of his lunch bag valid); cf. McDonell v. Hunter, 807 F.2d 1302, 1310 (8th Cir. 1987) (“If a
search is unreasonable, a government employer cannot require that its employees consent to that
search as a condition of employment.”).
With respect to statutory issues, we have also concluded that, for the reasons set forth in
our prior opinion—and so long as participating federal agencies consistently adopt, implement,
and enforce model computer log-on banners or model computer-user agreements—the
deployment of the EINSTEIN 2.0 program on federal information systems complies with the
Wiretap Act, the Foreign Intelligence Surveillance Act, the Stored Communications Act, and the
pen register and trap and trace provisions of title 18 of the United States Code. We agree with
the analysis of these issues set forth in our prior opinion, and will not repeat it here.
Finally, we do not believe the EINSTEIN 2.0 program runs afoul of state wiretapping or
communication privacy laws. See, e.g,. Fla. Stat. Ann. § 934.03 (West Supp. 2009); 18 Pa.
Cons. Stat. Ann. § 5704(4) (West Supp. 2009); Md. Code Ann., Cts. & Jud. Proc. § 10-402(c)(3)
(LexisNexis 2006); Cal. Penal Code 631(a) (West 1999). To the extent that such laws purported
to apply to the conduct of federal agencies and agents conducting EINSTEIN 2.0 operations and
imposed requirements that exceeded those imposed by the federal statutes discussed above, they
would “stand[] as an obstacle to the accomplishment and execution of the full purposes and
objectives of Congress,” and be unenforceable under the Supremacy Clause. Hines v.
Davidowitz, 312 U.S. 52, 67 (1941); see also Geier v. American Honda Motor Co., 529 U.S. 861,
873 (2000) (same); Old Dominion Branch v. Austin, 418 U.S. 264, 273 n.5 (1974) (Executive
Order “may create rights protected against inconsistent state laws through the Supremacy
Clause”); Bansal v. Russ, 513 F. Supp. 2d 264, 283 (E.D. Pa. 2007) (concluding that “federal
officers participating in a federal investigation are not required to follow” state wiretapping law
containing additional requirements not present in the federal Wiretap Act, because in such
circumstances, “the state law would stand as an obstacle to federal law enforcement”); Johnson
v. Maryland, 254 U.S. 51 (1920); cf. United States v. Adams, 694 F.2d 200, 201 (9th Cir. 1980)
5
Opinions of the Office of Legal Counsel in Volume 33
(“evidence obtained from a consensual wiretap conforming to 18 U.S.C. § 2511(2)(c) is
admissible in federal court proceedings without regard to state law”).
/s/
DAVID J. BARRON
Acting Assistant Attorney General
6