Finally, a small win by the People against the Police State.
Restrictive 4th Amendment Search and Seizure cases favorable to
the People are quite rare.
UNITED STATES, PETITIONER
SUPREME COURT OF THE UNITED STATES
OCTOBER TERM, 2011
Argued November 8, 2011
Decided January 23, 2012
Respondent was convicted of drug trafficking and conspiracy charges.
The District Court suppressed GPS data from a vehicle parked outside
of respondent's residence, but held the remaining data admissible
because respondent had no reasonable expectation of privacy when the
vehicle was on a public street. The D.C. Circuit reversed, concluding
that admission of the evidence obtained by warrantless use of the GPS
device violated the Fourth Amendment. The Court held that the
Government's installation of a GPS device on a target's vehicle, and
its use of that device to monitor the vehicle's movements, constituted
a search under the Fourth Amendment. Accordingly, the judgment of the
Court of Appeals was affirmed.
NOTE: Where it is feasible, a syllabus (headnote) will be
released, as is being done in connection with this case, at the time
the opinion is issued. The syllabus constitutes no part of the opinion
of the Court but has been prepared by the Reporter of Decisions for
the convenience of the reader. See United States v. Detroit Timber &
Lumber Co., 200 U. S. 321, 337.
UNITED STATES v. JONES
CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
THE DISTRICT OF COLUMBIA CIRCUIT
The Government obtained a search warrant permitting it to
install a Global-Positioning-System (GPS) tracking device on a vehicle
registered to respondent Jones's wife. The warrant authorized
installation in the District of Columbia and within 10 days, but
agents installed the device on the 11th day and in Maryland. The
Government then tracked the vehicle's movements for 28 days. It
subsequently secured an indictment of Jones and others on drug
trafficking conspiracy charges. The District Court suppressed the GPS
data obtained while the vehicle was parked at Jones's residence, but
held the remaining data admissible because Jones had no reasonable
expectation of privacy when the vehicle was on public streets. Jones
was convicted. The D. C. Circuit reversed, concluding that admission
of the evidence obtained by warrantless use of the GPS device violated
the Fourth Amendment.
Held: The Government's attachment of the GPS device to the
vehicle, and its use of that device to monitor the vehicle's
movements, constitutes a search under the Fourth Amendment. Pp. 3-12.
(a) The Fourth Amendment protects the "right of the people to be
secure in their persons, houses, papers, and effects, against
unreasonable searches and seizures." Here, the Government's physical
intrusion on an "effect" for the purpose of obtaining information
constitutes a "search." This type of encroachment on an area
enumerated in the Amendment would have been considered a search within
the meaning of the Amendment at the time it was adopted. Pp. 3-4.
(b) This conclusion is consistent with this Court's Fourth Amendment
jurisprudence, which until the latter half of the 20th century was
tied to common-law trespass. Later cases, which have deviated from
that exclusively property-based approach, have applied the
analysis of Justice Harlan's concurrence in Katz v. United States, 389
U. S. 347, which said that the Fourth Amendment protects a person's
"reasonable expectation of privacy," id., at 360. Here, the Court need
not address the Government's contention that Jones had no "reasonable
expectation of privacy," because Jones's Fourth Amendment rights do
not rise or fall with the Katz formulation. At bottom, the Court must
"assur[e] preservation of that degree of privacy against government
that existed when the Fourth Amendment was adopted." Kyllo v. United
States, 533 U. S. 27, 34. Katz did not repudiate the understanding
that the Fourth Amendment embodies a particular concern for government
trespass upon the areas it enumerates. The Katz reasonable-
expectation-of-privacy test has been added to, but not substituted
for, the common-law trespassory test. See Alderman v. United States,
394 U. S. 165, 176; Soldal v. Cook County, 506 U. S. 56, 64. United
States v. Knotts, 460 U. S. 276, and United States v. Karo, 468 U. S.
705—post-Katz cases rejecting Fourth Amendment challenges to
"beepers," electronic tracking devices representing another form of
electronic monitoring—do not foreclose the conclusion that a search
occurred here. New York v. Class, 475 U. S. 106, and Oliver v. United
States, 466 U. S. 170, also do not support the Government's position.
(c) The Government's alternative argument—that if the attachment and
use of the device was a search, it was a reasonable one—is forfeited
because it was not raised below. P. 12.
615 F. 3d 544, affirmed.
SCALIA, J., delivered the opinion of the Court, in which
ROBERTS, C. J., and KENNEDY, THOMAS, and SOTOMAYOR, JJ., joined.
SOTOMAYOR, J., filed a concurring opinion. ALITO, J., filed an opinion
concurring in the judgment, in which GINSBURG, BREYER, and KAGAN, JJ.,
Opinion of the Court
NOTICE: This opinion is subject to formal revision before
publication in the preliminary print of the United States Reports.
Readers are requested to notify the Reporter of Decisions, Supreme
Court of the United States, Washington, D. C. 20543, of any
typographical or other formal errors, in order that corrections may be
made before the preliminary print goes to press.
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE DISTRICT OF COLUMBIA CIRCUIT
JUSTICE SCALIA delivered the opinion of the Court.
We decide whether the attachment of a Global-Positioning-
System (GPS) tracking device to an individual's vehicle, and
subsequent use of that device to monitor the vehicle's movements on
public streets, constitutes a search or seizure within the meaning of
the Fourth Amendment.
In 2004 respondent Antoine Jones, owner and operator of a
nightclub in the District of Columbia, came under suspicion of
trafficking in narcotics and was made the target of an investigation
by a joint FBI and Metropolitan Police Department task force. Officers
employed various investigative techniques, including visual
surveillance of the nightclub, installation of a camera focused on the
front door of the club, and a pen register and wiretap covering
Jones's cellular phone.
Based in part on information gathered from these sources, in
2005 the Government applied to the United States District Court for
the District of Columbia for a warrant authorizing the use of an
electronic tracking device on the Jeep Grand Cherokee registered to
wife. A warrant issued, authorizing installation of the device in the
District of Columbia and within 10 days.
On the 11th day, and not in the District of Columbia but in
Maryland,1 agents installed a GPS tracking device on the undercarriage
of the Jeep while it was parked in a public parking lot. Over the next
28 days, the Government used the device to track the vehicle's
movements, and once had to replace the device's battery when the
vehicle was parked in a different public lot in Maryland. By means of
signals from multiple satellites, the device established the vehicle's
location within 50 to 100 feet, and communicated that location by
cellular phone to a Government computer. It relayed more than 2,000
pages of data over the 4-week period.
The Government ultimately obtained a multiple-count indictment
charging Jones and several alleged co-conspirators with, as relevant
here, conspiracy to distribute and possess with intent to distribute
five kilograms or more of cocaine and 50 grams or more of cocaine
base, in violation of 21 U. S. C. §§841 and 846. Before trial, Jones
filed a motion to suppress evidence obtained through the GPS device.
The District Court granted the motion only in part, suppressing the
data obtained while the vehicle was parked in the garage adjoining
Jones's residence. 451 F. Supp. 2d 71, 88 (2006). It held the
remaining data admissible, because "'[a] person traveling in an
automobile on public thoroughfares has no reasonable expectation of
privacy in his movements from one place to another.'" Ibid. (quoting
United States v. Knotts, 460 U. S. 276, 281 (1983)). Jones's trial in
October 2006 produced a hung jury on the conspiracy count.
In March 2007, a grand jury returned another indict-
ment, charging Jones and others with the same conspiracy. The
Government introduced at trial the same GPS-derived locational data
admitted in the first trial, which connected Jones to the alleged
conspirators' stash house that contained $850,000 in cash, 97
kilograms of cocaine, and 1 kilogram of cocaine base. The jury
returned a guilty verdict, and the District Court sentenced Jones to
The United States Court of Appeals for the District of
Columbia Circuit reversed the conviction because of admission of the
evidence obtained by warrantless use of the GPS device which, it said,
violated the Fourth Amendment. United States v. Maynard, 615 F. 3d 544
(2010). The D. C. Circuit denied the Government's petition for
rehearing en banc, with four judges dissenting. 625 F. 3d 766 (2010).
We granted certiorari, 564 U. S. _ (2011).
The Fourth Amendment provides in relevant part that "[t]he
right of the people to be secure in their persons, houses, papers, and
effects, against unreasonable searches and seizures, shall not be
violated." It is beyond dispute that a vehicle is an "effect" as that
term is used in the Amendment. United States v. Chadwick, 433 U. S. 1,
12 (1977). We hold that the Government's installation of a GPS device
on a target's vehicle,2 and its use of that device to monitor the
vehicle's movements, constitutes a "search."
It is important to be clear about what occurred in this case:
The Government physically occupied private property for the purpose of
obtaining information. We have no doubt that such a physical intrusion
would have been considered a "search" within the meaning of the Fourth
Amendment when it was adopted. Entick v. Carrington, 95 Eng. Rep. 807
(C. P. 1765), is a "case we have described as a 'monument of English
freedom' 'undoubtedly familiar' to 'every American statesman' at the
time the Constitution was adopted, and considered to be 'the true and
ultimate expression of constitutional law'" with regard to search and
seizure. Brower v. County of Inyo, 489 U. S. 593, 596 (1989) (quoting
Boyd v. United States, 116 U. S. 616, 626 (1886)). In that case, Lord
Camden expressed in plain terms the significance of property rights in
"[O]ur law holds the property of every man so sacred, that no man can
set his foot upon his neighbour's close without his leave; if he does
he is a trespasser, though he does no damage at all; if he will tread
upon his neighbour's ground, he must justify it by law." Entick,
supra, at 817.
The text of the Fourth Amendment reflects its close connection to
property, since otherwise it would have referred simply to "the right
of the people to be secure against unreasonable searches and
seizures"; the phrase "in their persons, houses, papers, and effects"
would have been superfluous.
Consistent with this understanding, our Fourth Amendment
jurisprudence was tied to common-law trespass, at least until the
latter half of the 20th century. Kyllo v. United States, 533 U. S. 27,
31 (2001); Kerr, The Fourth Amendment and New Technologies:
Constitutional Myths and the Case for Caution, 102 Mich. L. Rev. 801,
816 (2004). Thus, in Olmstead v. United States, 277 U. S.
438 (1928), we held that wiretaps attached to telephone wires on the
public streets did not constitute a Fourth Amendment search because
"[t]here was no entry of the houses or offices of the defendants,"
id., at 464.
Our later cases, of course, have deviated from that
exclusively property-based approach. In Katz v. United States, 389 U.
S. 347, 351 (1967), we said that "the Fourth Amendment protects
people, not places," and found a violation in attachment of an
eavesdropping device to a public telephone booth. Our later cases have
applied the analysis of Justice Harlan's concurrence in that case,
which said that a violation occurs when government officers violate a
person's "reasonable expectation of privacy," id., at 360. See, e.g.,
Bond v. United States, 529 U. S. 334 (2000); California v. Ciraolo,
476 U. S. 207 (1986); Smith v. Maryland, 442 U. S. 735 (1979).
The Government contends that the Harlan standard shows that no
search occurred here, since Jones had no "reasonable expectation of
privacy" in the area of the Jeep accessed by Government agents (its
underbody) and in the locations of the Jeep on the public roads, which
were visible to all. But we need not address the Government's
contentions, because Jones's Fourth Amendment rights do not rise or
fall with the Katz formulation. At bottom, we must "assur[e]
preservation of that degree of privacy against government that existed
when the Fourth Amendment was adopted." Kyllo, supra, at 34. As
explained, for most of our history the Fourth Amendment was understood
to embody a particular concern for government trespass upon the areas
("persons, houses, papers, and effects") it enumerates.3 Katz did not
that understanding. Less than two years later the Court upheld
defendants' contention that the Government could not introduce against
them conversations between other people obtained by warrantless
placement of electronic surveillance devices in their homes. The
opinion rejected the dissent's contention that there was no Fourth
Amendment violation "unless the conversational privacy of the
homeowner himself is invaded."4 Alderman v. United States, 394 U. S.
165, 176 (1969). "[W]e [do not] believe that Katz, by holding that the
Fourth Amendment protects persons and their private conversations, was
intended to withdraw any of the protection which the Amendment extends
to the home . . . ." Id., at 180.
More recently, in Soldal v. Cook County, 506 U. S. 56 (1992),
the Court unanimously rejected the argument that although a "seizure"
had occurred "in a 'technical' sense" when a trailer home was forcibly
removed, id., at 62, no Fourth Amendment violation occurred because
law enforcement had not "invade[d] the [individuals'] privacy," id.,
at 60. Katz, the Court explained, established that "property rights
are not the sole measure of Fourth
Amendment violations," but did not "snuf[f] out the previously
recognized protection for property." 506 U. S., at 64. As Justice
Brennan explained in his concurrence in Knotts, Katz did not erode the
principle "that, when the Government does engage in physical intrusion
of a constitutionally protected area in order to obtain information,
that intrusion may constitute a violation of the Fourth Amendment."
460 U. S., at 286 (opinion concurring in judgment). We have embodied
that preservation of past rights in our very definition of "reasonable
expectation of privacy" which we have said to be an expectation "that
has a source outside of the Fourth Amendment, either by reference to
concepts of real or personal property law or to understandings that
are recognized and permitted by society." Minnesota v. Carter, 525 U.
S. 83, 88 (1998) (internal quotation marks omitted). Katz did not
narrow the Fourth Amendment's scope.5
The Government contends that several of our post-Katz cases
foreclose the conclusion that what occurred here constituted a search.
It relies principally on two cases in
which we rejected Fourth Amendment challenges to "beepers," electronic
tracking devices that represent another form of electronic monitoring.
The first case, Knotts, upheld against Fourth Amendment challenge the
use of a "beeper" that had been placed in a container of chloroform,
allowing law enforcement to monitor the location of the container. 460
U. S., at 278. We said that there had been no infringement of Knotts'
reasonable expectation of privacy since the information obtained—the
location of the automobile carrying the container on public roads, and
the location of the off-loaded container in open fields near Knotts'
cabin—had been voluntarily conveyed to the pub-lic.6 Id., at 281-282.
But as we have discussed, the Katz reasonable-expectation-of-privacy
test has been added to, not substituted for, the common-law
trespassory test. The holding in Knotts addressed only the former,
since the latter was not at issue. The beeper had been placed in the
container before it came into Knotts' possession, with the consent of
the then-owner. 460 U. S., at 278. Knotts did not challenge that
installation, and we specifically declined to consider its effect on
the Fourth Amendment analysis. Id., at 279, n. Knotts would be
relevant, perhaps, if the Government were making the argument that
what would otherwise be an unconstitutional search is not such where
it produces only public information. The Government does not make that
argument, and we know of no case that would support it.
The second "beeper" case, United States v. Karo, 468 U. S. 705
(1984), does not suggest a different conclusion. There we addressed
the question left open by Knotts, whether the installation of a beeper
in a container
amounted to a search or seizure. 468 U. S., at 713. As in Knotts, at
the time the beeper was installed the container belonged to a third
party, and it did not come into possession of the defendant until
later. 468 U. S., at 708. Thus, the specific question we considered
was whether the installation "with the consent of the original owner
consti-tute[d] a search or seizure . . . when the container is
delivered to a buyer having no knowledge of the presence of the
beeper." Id., at 707 (emphasis added). We held not. The Government, we
said, came into physical contact with the container only before it
belonged to the defendant Karo; and the transfer of the container with
the unmonitored beeper inside did not convey any information and thus
did not invade Karo's privacy. See id., at 712. That conclusion is
perfectly consistent with the one we reach here. Karo accepted the
container as it came to him, beeper and all, and was therefore not
entitled to object to the beeper's presence, even though it was used
to monitor the container's location. Cf. On Lee v. United States, 343
U. S. 747, 751-752 (1952) (no search or seizure where an informant,
who was wearing a concealed microphone, was invited into the
defendant's business). Jones, who possessed the Jeep at the time the
Government trespassorily inserted the information-gathering device, is
on much different footing.
The Government also points to our exposition in New York v.
Class, 475 U. S. 106 (1986), that "[t]he exterior of a car . . . is
thrust into the public eye, and thus to examine it does not constitute
a 'search.'" Id., at 114. That statement is of marginal relevance here
since, as the Government acknowledges, "the officers in this case did
more than conduct a visual inspection of respondent's vehicle," Brief
for United States 41 (emphasis added). By attaching the device to the
Jeep, officers encroached on a protected area. In Class itself we
suggested that this would make a difference, for we concluded that an
officer's momentary reaching into the interior of a vehicle did
search.7 475 U. S., at 114-115.
Finally, the Government's position gains little support from
our conclusion in Oliver v. United States, 466 U. S. 170 (1984), that
officers' information-gathering intrusion on an "open field" did not
constitute a Fourth Amendment search even though it was a trespass at
common law, id., at 183. Quite simply, an open field, unlike the
curtilage of a home, see United States v. Dunn, 480 U. S. 294, 300
(1987), is not one of those protected areas enumerated in the Fourth
Amendment. Oliver, supra, at 176-177. See also Hester v. United
States, 265 U. S. 57, 59 (1924). The Government's physical intrusion
on such an area—unlike its intrusion on the "effect" at issue here—is
of no Fourth Amendment significance.8
The concurrence begins by accusing us of applying "18th-
century tort law." Post, at 1. That is a distortion. What we apply is
an 18th-century guarantee against unreasonable searches, which we
believe must provide at
a minimum the degree of protection it afforded when it was adopted.
The concurrence does not share that belief. It would apply exclusively
Katz's reasonable-expectation-of-privacy test, even when that
eliminates rights that previously existed.
The concurrence faults our approach for "present[ing]
particularly vexing problems" in cases that do not involve physical
contact, such as those that involve the transmission of electronic
signals. Post, at 9. We entirely fail to understand that point. For
unlike the concurrence, which would make Katz the exclusive test, we
do not make trespass the exclusive test. Situations involving merely
the transmission of electronic signals without trespass would remain
subject to Katz analysis.
In fact, it is the concurrence's insistence on the exclusivity
of the Katz test that needlessly leads us into "particularly vexing
problems" in the present case. This Court has to date not deviated
from the understanding that mere visual observation does not
constitute a search. See Kyllo, 533 U. S., at 31-32. We accordingly
held in Knotts that "[a] person traveling in an automobile on public
thoroughfares has no reasonable expectation of privacy in his
movements from one place to another." 460 U. S., at 281. Thus, even
assuming that the concurrence is correct to say that "[t]raditional
surveillance" of Jones for a 4-week period "would have required a
large team of agents, multiple vehicles, and perhaps aerial
assistance," post, at 12, our cases suggest that such visual
observation is constitutionally permissible. It may be that achieving
the same result through electronic means, without an accompanying
trespass, is an unconstitutional invasion of privacy, but the present
case does not require us to answer that question.
And answering it affirmatively leads us needlessly into
additional thorny problems. The concurrence posits that "relatively
short-term monitoring of a person's movements
on public streets" is okay, but that "the use of longer term GPS
monitoring in investigations of most offenses" is no good. Post, at 13
(emphasis added). That introduces yet another novelty into our
jurisprudence. There is no precedent for the proposition that whether
a search has occurred depends on the nature of the crime being
investigated. And even accepting that novelty, it remains unexplained
why a 4-week investigation is "surely" too long and why a drug-
trafficking conspiracy involving substantial amounts of cash and
narcotics is not an "extraordinary offens[e]" which may permit longer
observation. See post, at 13-14. What of a 2-day monitoring of a
suspected purveyor of stolen electronics? Or of a 6-month monitoring
of a suspected terrorist? We may have to grapple with these "vexing
problems" in some future case where a classic trespassory search is
not involved and resort must be had to Katz analysis; but there is no
reason for rushing forward to resolve them here.
The Government argues in the alternative that even if the
attachment and use of the device was a search, it was reasonable—and
thus lawful—under the Fourth Amendment because "officers had
reasonable suspicion, and indeed probable cause, to believe that
[Jones] was a leader in a large-scale cocaine distribution
conspiracy." Brief for United States 50-51. We have no occasion to
consider this argument. The Government did not raise it below, and the
D. C. Circuit therefore did not address it. See 625 F. 3d, at 767
(Ginsburg, Tatel, and Griffith, JJ., concurring in denial of rehearing
en banc). We consider the argument forfeited. See Sprietsma v. Mercury
Marine, 537 U. S. 51, 56, n. 4 (2002).
* * *
The judgment of the Court of Appeals for the D. C. Circuit is
It is so ordered.
SOTOMAYOR, J., concurring
UNITED STATES, PETITIONER
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE DISTRICT OF COLUMBIA CIRCUIT
JUSTICE SOTOMAYOR, concurring.
I join the Court's opinion because I agree that a search
within the meaning of the Fourth Amendment occurs, at a minimum, "[w]
here, as here, the Government obtains information by physically
intruding on a constitutionally protected area." Ante, at 6, n. 3. In
this case, the Government installed a Global Positioning System (GPS)
tracking device on respondent Antoine Jones' Jeep without a valid
warrant and without Jones' consent, then used that device to monitor
the Jeep's movements over the course of four weeks. The Government
usurped Jones' property for the purpose of conducting surveillance on
him, thereby invading privacy interests long afforded, and undoubtedly
entitled to, Fourth Amendment protection. See, e.g., Silverman v.
United States, 365 U. S. 505, 511-512 (1961).
Of course, the Fourth Amendment is not concerned only with
trespassory intrusions on property. See, e.g., Kyllo v. United States,
533 U. S. 27, 31-33 (2001). Rather, even in the absence of a trespass,
"a Fourth Amendment search occurs when the government violates a
subjective expectation of privacy that society recognizes as
reasonable." Id., at 33; see also Smith v. Maryland, 442 U. S. 735,
740-741 (1979); Katz v. United States, 389 U. S. 347, 361 (1967)
(Harlan, J., concurring). In Katz, this Court enlarged its then-
prevailing focus on property rights by announcing
that the reach of the Fourth Amendment does not "turn upon the
presence or absence of a physical intrusion." Id., at 353. As the
majority's opinion makes clear, however, Katz's reasonable-
expectation-of-privacy test augmented, but did not displace or
diminish, the common-law trespassory test that preceded it. Ante, at
8. Thus, "when the Government does engage in physical intrusion of a
constitutionally protected area in order to obtain information, that
intrusion may constitute a violation of the Fourth Amendment." United
States v. Knotts, 460 U. S. 276, 286 (1983) (Brennan, J., concurring
in judgment); see also, e.g., Rakas v. Illinois, 439 U. S. 128, 144,
n. 12 (1978). JUSTICE ALITO's approach, which discounts altogether the
constitutional relevance of the Government's physical intrusion on
Jones' Jeep, erodes that longstanding protection for privacy
expectations inherent in items of property that people possess or
control. See post, at 5—7 (opinion concurring in judgment). By
contrast, the trespassory test applied in the majority's opinion
reflects an irreducible constitutional minimum: When the Government
physically invades personal property to gather information, a search
occurs. The reaffirmation of that principle suffices to decide this
Nonetheless, as JUSTICE ALITO notes, physical intrusion is now
unnecessary to many forms of surveillance. Post, at 9—12. With
increasing regularity, the Government will be capable of duplicating
the monitoring undertaken in this case by enlisting factory- or
owner-installed vehicle tracking devices or GPS-enabled smartphones.
See United States v. Pineda-Moreno, 617 F. 3d 1120, 1125 (CA9 2010)
(Kozinski, C. J., dissenting from denial of rehearing en banc). In
cases of electronic or other novel modes of surveillance that do not
depend upon a physical invasion on property, the majority opinion's
trespassory test may provide little guidance. But "[s]ituations
involving merely the transmission of electronic signals without
would remain subject to Katz analysis." Ante, at 11. As JUSTICE ALITO
incisively observes, the same technological advances that have made
possible nontrespassory surveillance techniques will also affect the
Katz test by shaping the evolution of societal privacy expectations.
Post, at 10—11. Under that rubric, I agree with JUSTICE ALITO that, at
the very least, "longer term GPS monitoring in investigations of most
offenses impinges on expectations of privacy." Post, at 13.
In cases involving even short-term monitoring, some unique
attributes of GPS surveillance relevant to the Katz analysis will
require particular attention. GPS monitoring generates 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, e.g., People v. Weaver, 12 N.
Y. 3d 433, 441—442, 909 N. E. 2d 1195, 1199 (2009) ("Disclosed in
[GPS] data . . . will be trips the indisputably private nature of
which takes little imagination to conjure: trips to the psychiatrist,
the plastic surgeon, the abortion clinic, the AIDS treatment center,
the strip club, the criminal defense attorney, the by-the-hour motel,
the union meeting, the mosque, synagogue or church, the gay bar and on
and on"). The Government can store such records and efficiently mine
them for information years into the future. Pineda-Moreno, 617 F. 3d,
at 1124 (opinion of Kozinski, C. J.). And because GPS monitoring is
cheap in comparison to conventional surveillance techniques and, by
design, proceeds surreptitiously, it evades the ordinary checks that
constrain abusive law enforcement practices: "limited police resources
and community hostility." Illinois v. Lidster, 540 U. S. 419, 426
Awareness that the Government may be watching chills
associational and expressive freedoms. And the Government's
unrestrained power to assemble data that reveal private aspects of
identity is susceptible to abuse. The net
result is that GPS monitoring—by making available at a relatively low
cost such a substantial quantum of intimate information about any
person whom the Government, in its unfettered discretion, chooses to
track—may "alter the relationship between citizen and government in a
way that is inimical to democratic society." United States v. Cuevas-
Perez, 640 F. 3d 272, 285 (CA7 2011) (Flaum, J., concurring).
I would take these attributes of GPS monitoring into account
when considering the existence of a reasonable societal expectation of
privacy in the sum of one's public movements. I would ask whether
people reasonably expect that their movements will be recorded and
aggregated in a manner that enables the Government to ascertain, more
or less at will, their political and religious beliefs, sexual habits,
and so on. I do not regard as dispositive the fact that the Government
might obtain the fruits of GPS monitoring through lawful conventional
surveillance techniques. See Kyllo, 533 U. S., at 35, n. 2; ante, at
11 (leaving open the possibility that duplicating traditional
surveillance "through electronic means, without an accompanying
trespass, is an unconstitutional invasion of privacy"). I would also
consider the appropriateness of entrusting to the Executive, in the
absence of any oversight from a coordinate branch, a tool so amenable
to misuse, especially in light of the Fourth Amendment's goal to curb
arbitrary exercises of police power to and prevent "a too permeating
police surveillance," United States v. Di Re, 332 U. S. 581, 595
More fundamentally, it may be necessary to reconsider the
premise that an individual has no reasonable expectation of privacy in
information voluntarily disclosed to third parties. E.g., Smith, 442
U. S., at 742; United States v. Miller, 425 U. S. 435, 443 (1976).
This approach is ill suited to the digital age, in which people reveal
a great deal of information about themselves to third parties in the
course of carrying out mundane tasks. People disclose the phone
numbers that they dial or text to their cellular providers; the URLs
that they visit and the e-mail addresses with which they correspond to
their Internet service providers; and the books, groceries, and
medications they purchase to online retailers. Perhaps, as JUSTICE
ALITO notes, some people may find the "tradeoff" of privacy for
convenience "worthwhile," or come to accept this "diminution of
privacy" as "inevitable," post, at 10, and perhaps not. I for one
doubt that people would accept without complaint the warrantless
disclosure to the Government of a list of every Web site they had
visited in the last week, or month, or year. But whatever the societal
expectations, they can attain constitutionally protected status only
if our Fourth Amendment jurisprudence ceases
to treat secrecy as a prerequisite for privacy. I would not assume
that all information voluntarily disclosed to some member of the
public for a limited purpose is, for that reason alone, disentitled to
Fourth Amendment protection. See Smith, 442 U. S., at 749 (Marshall,
J., dissenting) ("Privacy is not a discrete commodity, possessed
absolutely or not at all. Those who disclose certain facts to a bank
or phone company for a limited business purpose need not assume that
this information will be released to other persons for other
purposes"); see also Katz, 389 U. S., at 351-352 ("[W]hat [a person]
seeks to preserve as private, even in an area accessible to the
public, may be constitutionally protected").
Resolution of these difficult questions in this case is
unnecessary, however, because the Government's physical intrusion on
Jones' Jeep supplies a narrower basis for decision. I therefore join
the majority's opinion.
ALITO, J., concurring in judgment
UNITED STATES, PETITIONER
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE DISTRICT OF COLUMBIA CIRCUIT
JUSTICE ALITO, with whom JUSTICE GINSBURG, JUSTICE BREYER, and
JUSTICE KAGAN join, concurring in the judgment.
This case requires us to apply the Fourth Amendment's
prohibition of unreasonable searches and seizures to a 21st-century
surveillance technique, the use of a Global Positioning System (GPS)
device to monitor a vehicle's movements for an extended period of
time. Ironically, the Court has chosen to decide this case based on
18th-century tort law. By attaching a small GPS device9 to the
underside of the vehicle that respondent drove, the law enforcement
officers in this case engaged in conduct that might have provided
grounds in 1791 for a suit for trespass to chattels.10 And for this
reason, the Court concludes, the installation and use of the GPS
device constituted a search. Ante, at 3-4.
This holding, in my judgment, is unwise. It strains the
language of the Fourth Amendment; it has little if any support in
current Fourth Amendment case law; and it is highly artificial.
I would analyze the question presented in this case by asking
whether respondent's reasonable expectations of privacy were violated
by the long-term monitoring of the movements of the vehicle he drove.
The Fourth Amendment prohibits "unreasonable searches and
seizures," and the Court makes very little effort to explain how the
attachment or use of the GPS device fits within these terms. The Court
does not contend that there was a seizure. A seizure of property
occurs when there is "some meaningful interference with an
individual's possessory interests in that property," United States v.
Jacobsen, 466 U. S. 109, 113 (1984), and here there was none. Indeed,
the success of the surveillance technique that the officers employed
was dependent on the fact that the GPS did not interfere in any way
with the operation of the vehicle, for if any such interference had
been detected, the device might have been discovered.
The Court does claim that the installation and use of the GPS
constituted a search, see ante, at 3-4, but this conclusion is
dependent on the questionable proposition that these two procedures
cannot be separated for purposes of Fourth Amendment analysis. If
these two procedures are analyzed separately, it is not at all clear
from the Court's opinion why either should be regarded as a search. It
is clear that the attachment of the GPS device was not itself a
search; if the device had not functioned or if the officers had not
used it, no information would have been obtained. And the Court does
not contend that the use of the device constituted a search either. On
the contrary, the Court
accepts the holding in United States v. Knotts, 460 U. S. 276 (1983),
that the use of a surreptitiously planted electronic device to monitor
a vehicle's movements on public roads did not amount to a search. See
ante, at 7.
The Court argues—and I agree—that "we must 'assur[e]
preservation of that degree of privacy against government that existed
when the Fourth Amendment was adopted.'" Ante, at 5 (quoting Kyllo v.
United States, 533 U. S. 27, 34 (2001)). But it is almost impossible
to think of late-18th-century situations that are analogous to what
took place in this case. (Is it possible to imagine a case in which a
constable secreted himself somewhere in a coach and remained there for
a period of time in order to monitor the movements of the coach's
owner?11 ) The Court's theory seems to be that the concept of a
search, as originally understood, comprehended any technical trespass
that led to the gathering of evidence, but we know that this is
incorrect. At common law, any unauthorized intrusion on private
property was actionable, see Prosser & Keeton 75, but a trespass on
open fields, as opposed to the "curtilage" of a home, does not fall
within the scope of the Fourth Amendment because private property
outside the curtilage is not part of a "hous[e]" within the meaning of
the Fourth Amendment. See Oliver v. United States, 466 U. S. 170
(1984); Hester v. United States, 265 U. S. 57 (1924).
The Court's reasoning in this case is very similar to that in
the Court's early decisions involving wiretapping and electronic
eavesdropping, namely, that a technical trespass followed by the
gathering of evidence constitutes a
search. In the early electronic surveillance cases, the Court
concluded that a Fourth Amendment search occurred when private
conversations were monitored as a result of an "unauthorized physical
penetration into the premises occupied" by the defendant. Silverman v.
United States, 365 U. S. 505, 509 (1961). In Silverman, police
officers listened to conversations in an attached home by inserting a
"spike mike" through the wall that this house shared with the vacant
house next door. Id., at 506. This procedure was held to be a search
because the mike made contact with a heating duct on the other side of
the wall and thus "usurp[ed] . . . an integral part of the premises."
Id., at 511.
By contrast, in cases in which there was no trespass, it was
held that there was no search. Thus, in Olmstead v. United States, 277
U. S. 438 (1928), the Court found that the Fourth Amendment did not
apply because "[t]he taps from house lines were made in the streets
near the houses." Id., at 457. Similarly, the Court concluded that no
search occurred in Goldman v. United States, 316 U. S. 129, 135
(1942), where a "detectaphone" was placed on the outer wall of
defendant's office for the purpose of overhearing conversations held
within the room.
This trespass-based rule was repeatedly criticized. In
Olmstead, Justice Brandeis wrote that it was "immaterial where the
physical connection with the telephone wires was made." 277 U. S., at
479 (dissenting opinion). Although a private conversation transmitted
by wire did not fall within the literal words of the Fourth Amendment,
he argued, the Amendment should be understood as prohibiting "every
unjustifiable intrusion by the government upon the privacy of the
individual." Id., at 478. See also, e.g., Silverman, supra, at 513
(Douglas, J., concurring) ("The concept of 'an unauthorized physical
penetration into the premises,' on which the present decision rests
seems to me beside the point. Was not the wrong . . . done when the
intimacies of the home were tapped, recorded, or revealed? The depth
of the penetration of the electronic device—even the degree of its
remoteness from the inside of the house— is not the measure of the
injury"); Goldman, supra, at 139 (Murphy, J., dissenting) ("[T]he
search of one's home or office no longer requires physical entry, for
science has brought forth far more effective devices for the invasion
of a person's privacy than the direct and obvious methods of
oppression which were detested by our forebears and which inspired the
Katz v. United States, 389 U. S. 347 (1967), finally did away
with the old approach, holding that a trespass was not required for a
Fourth Amendment violation. Katz involved the use of a listening
device that was attached to the outside of a public telephone booth
and that allowed police officers to eavesdrop on one end of the
target's phone conversation. This procedure did not physically intrude
on the area occupied by the target, but the Katz Court, "repudiate
[ed]" the old doctrine, Rakas v. Illinois, 439 U. S. 128, 143 (1978),
and held that "[t]he fact that the electronic device employed . . .
did not happen to penetrate the wall of the booth can have no
constitutional significance," 389 U. S., at 353 ("[T]he reach of th[e]
[Fourth] Amendment cannot turn upon the presence or absence of a
physical intrusion into any given enclosure"); see Rakas, supra, at
143 (describing Katz as holding that the "capacity to claim the
protection for the Fourth Amendment depends not upon a property right
in the invaded place but upon whether the person who claims the
protection of the Amendment has a legitimate expectation of privacy in
the invaded place"); Kyllo, supra, at 32 ("We have since decoupled
violation of a person's Fourth Amendment rights from trespassory
violation of his property"). What mattered, the Court now held, was
whether the conduct at issue "violated the privacy upon which [the
defendant] justifiably relied while using the telephone booth." Katz,
Under this approach, as the Court later put it when addressing
the relevance of a technical trespass, "an actual trespass is neither
necessary nor sufficient to establish a constitutional violation."
United States v. Karo, 468 U. S. 705, 713 (1984) (emphasis added).
Ibid. ("Compar[ing] Katz v. United States, 389 U. S. 347 (1967) (no
trespass, but Fourth Amendment violation), with Oliver v. United
States, 466 U. S. 170 (1984) (trespass, but no Fourth Amendment
violation)"). In Oliver, the Court wrote:
"The existence of a property right is but one element in determining
whether expectations of privacy are legitimate. 'The premise that
property interests control the right of the Government to search and
seize has been discredited.' Katz, 389 U. S., at 353, (quoting Warden
v. Hayden, 387 U. S. 294, 304 (1967); some internal quotation marks
omitted)." 466 U. S., at 183.
The majority suggests that two post-Katz decisions— Soldal v.
Cook County, 506 U. S. 56 (1992), and Alderman v. United States, 394
U. S. 165 (1969)—show that a technical trespass is sufficient to
establish the existence of a search, but they provide little support.
In Soldal, the Court held that towing away a trailer home
without the owner's consent constituted a seizure even if this did not
invade the occupants' personal privacy. But in the present case, the
Court does not find that there was a seizure, and it is clear that
In Alderman, the Court held that the Fourth Amendment rights
of homeowners were implicated by the use of a surreptitiously planted
listening device to monitor third-party conversations that occurred
within their home. See 394 U. S., at 176-180. Alderman is best
mean that the homeowners had a legitimate expectation of privacy in
all conversations that took place under their roof. See Rakas, 439 U.
S., at 144, n. 12 (citing Alderman for the proposition that "the Court
has not altogether abandoned use of property concepts in determining
the presence or absence of the privacy interests protected by that
Amendment"); 439 U. S., at 153 (Powell, J., concurring) (citing
Alderman for the proposition that "property rights reflect society's
explicit recognition of a person's authority to act as he wishes in
certain areas, and therefore should be considered in determining
whether an individual's expectations of privacy are reasonable); Karo,
supra, at 732 (Stevens, J., concurring in part and dissenting in part)
(citing Alderman in support of the proposition that "a homeowner has a
reasonable expectation of privacy in the contents of his home,
including items owned by others").
In sum, the majority is hard pressed to find support in post-
Katz cases for its trespass-based theory.
Disharmony with a substantial body of existing case law is
only one of the problems with the Court's approach in this case.
I will briefly note four others. First, the Court's reasoning
largely disregards what is really important (the use of a GPS for the
purpose of long-term tracking) and instead attaches great significance
to something that most would view as relatively minor (attaching to
the bottom of a car a small, light object that does not interfere in
any way with the car's operation). Attaching such an object is
generally regarded as so trivial that it does not provide a basis for
recovery under modern tort law. See Prosser & Keeton §14, at 87
(harmless or trivial contact with personal property not actionable);
D. Dobbs, Law of Torts 124 (2000) (same). But under the Court's
reasoning, this conduct
may violate the Fourth Amendment. By contrast, if long-term monitoring
can be accomplished without committing a technical trespass—suppose,
for example, that the Federal Government required or persuaded auto
manufacturers to include a GPS tracking device in every car—the
Court's theory would provide no protection.
Second, the Court's approach leads to incongruous results. If
the police attach a GPS device to a car and use the device to follow
the car for even a brief time, under the Court's theory, the Fourth
Amendment applies. But if the police follow the same car for a much
longer period using unmarked cars and aerial assistance, this tracking
is not subject to any Fourth Amendment constraints.
In the present case, the Fourth Amendment applies, the Court
concludes, because the officers installed the GPS device after
respondent's wife, to whom the car was registered, turned it over to
respondent for his exclusive use. See ante, at 8. But if the GPS had
been attached prior to that time, the Court's theory would lead to a
different result. The Court proceeds on the assumption that respondent
"had at least the property rights of a bailee," ante, at 3, n. 2, but
a bailee may sue for a trespass to chattel only if the injury occurs
during the term of the bailment. See 8A Am. Jur. 2d, Bailment §166,
pp. 685686 (2009). So if the GPS device had been installed before
respondent's wife gave him the keys, respondent would have no claim
for trespass—and, presumably, no Fourth Amendment claim either.
Third, under the Court's theory, the coverage of the Fourth
Amendment may vary from State to State. If the events at issue here
had occurred in a community property State12 or a State that has
adopted the Uniform Marital
Property Act,13 respondent would likely be an owner of the vehicle,
and it would not matter whether the GPS was installed before or after
his wife turned over the keys. In non-community-property States, on
the other hand, the registration of the vehicle in the name of
respondent's wife would generally be regarded as presumptive evidence
that she was the sole owner. See 60 C. J. S., Motor Vehicles §231, pp.
398-399 (2002); 8 Am. Jur. 2d, Automobiles §1208, pp. 859-860 (2007).
Fourth, the Court's reliance on the law of trespass will
present particularly vexing problems in cases involving surveillance
that is carried out by making electronic, as opposed to physical,
contact with the item to be tracked. For example, suppose that the
officers in the present case had followed respondent by
surreptitiously activating a stolen vehicle detection system that came
with the car when it was purchased. Would the sending of a radio
signal to activate this system constitute a trespass to chattels?
Trespass to chattels has traditionally required a physical touching of
the property. See Restatement (Second) of Torts §217 and Comment e
(1963 and 1964); Dobbs, supra, at 123. In recent years, courts have
wrestled with the application of this old tort in cases involving
unwanted electronic contact with computer systems, and some have held
that even the transmission of electrons that occurs when a
communication is sent from one computer to another is enough. See,
e.g., CompuServe, Inc. v. Cyber Promotions, Inc.,962 F. Supp. 1015 (SD
Ohio 1997); Thrifty-Tel, Inc. v. Bezenek, 46 Cal. App. 4th 1559, 1566,
n. 6 (1996). But may such decisions be followed in applying the
Court's trespass theory? Assuming that what matters under the Court's
theory is the law of trespass as it existed at the time of the
adoption of the Fourth
Amendment, do these recent decisions represent a change in the law or
simply the application of the old tort to new situations?
The Katz expectation-of-privacy test avoids the problems and
complications noted above, but it is not without its own difficulties.
It involves a degree of circularity, see Kyllo, 533 U. S., at 34, and
judges are apt to confuse their own expectations of privacy with those
of the hypothetical reasonable person to which the Katz test looks.
See Minnesota v. Carter, 525 U. S. 83, 97 (1998) (SCALIA, J.,
concurring). In addition, the Katz test rests on the assumption that
this hypothetical reasonable person has a well-developed and stable
set of privacy expectations. But technology can change those
expectations. Dramatic technological change may lead to periods in
which popular expectations are in flux and may ultimately produce
significant changes in popular attitudes. New technology may provide
increased convenience or security at the expense of privacy, and many
people may find the tradeoff worthwhile. And even if the public does
not welcome the diminution of privacy that new technology entails,
they may eventually reconcile themselves to this development as
On the other hand, concern about new intrusions on privacy may
spur the enactment of legislation to protect against these intrusions.
This is what ultimately happened with respect to wiretapping. After
did not leave it to the courts to develop a body of Fourth Amendment
case law governing that complex subject. Instead, Congress promptly
enacted a comprehensive statute, see 18 U. S. C. §§2510-2522 (2006 ed.
and Supp. IV), and since that time, the regulation of wiretapping has
been governed primarily by statute and not by case law.15 In an ironic
sense, although Katz overruled Olmstead, Chief Justice Taft's
suggestion in the latter case that the regulation of wiretapping was a
matter better left for Congress, see 277 U. S., at 465-466, has been
Recent years have seen the emergence of many new devices that
permit the monitoring of a person's movements. In some locales,
closed-circuit television video monitoring is becoming ubiquitous. On
toll roads, automatic toll collection systems create a precise record
of the movements of motorists who choose to make use of that
convenience. Many motorists purchase cars that are equipped with
devices that permit a central station to ascertain the car's location
at any time so that roadside assistance may be provided if needed and
the car may be found if it is stolen.
Perhaps most significant, cell phones and other wireless
devices now permit wireless carriers to track and record the location
of users—and as of June 2011, it has been reported, there were more
than 322 million wireless devices in use in the United States.16 For
older phones, the accuracy of the location information depends on the
density of the tower network, but new "smart phones," which
are equipped with a GPS device, permit more precise tracking. For
example, when a user activates the GPS on such a phone, a provider is
able to monitor the phone's location and speed of movement and can
then report back real-time traffic conditions after combining
("crowdsourcing") the speed of all such phones on any particular
road.17 Similarly, phone-location-tracking services are offered as
"social" tools, allowing consumers to find (or to avoid) others who
enroll in these services. The availability and use of these and other
new devices will continue to shape the average person's expectations
about the privacy of his or her daily movements.
In the pre-computer age, the greatest protections of privacy
were neither constitutional nor statutory, but practical. Traditional
surveillance for any extended period of time was difficult and costly
and therefore rarely undertaken. The surveillance at issue in this
case—constant monitoring of the location of a vehicle for four weeks—
would have required a large team of agents, multiple vehicles, and
perhaps aerial assistance.18 Only an investigation of unusual
importance could have justified such an
expenditure of law enforcement resources. Devices like the one used in
the present case, however, make long-term monitoring relatively easy
and cheap. In circumstances involving dramatic technological change,
the best solution to privacy concerns may be legislative. See, e.g.,
Kerr, 102 Mich. L. Rev., at 805-806. A legislative body is well
situated to gauge changing public attitudes, to draw detailed lines,
and to balance privacy and public safety in a comprehensive way.
To date, however, Congress and most States have not enacted
statutes regulating the use of GPS tracking technology for law
enforcement purposes. The best that we can do in this case is to apply
existing Fourth Amendment doctrine and to ask whether the use of GPS
tracking in a particular case involved a degree of intrusion that a
reasonable person would not have anticipated.
Under this approach, relatively short-term monitoring of a
person's movements on public streets accords with expectations of
privacy that our society has recognized as reasonable. See Knotts, 460
U. S., at 281-282. But the use of longer term GPS monitoring in
investigations of most offenses impinges on expectations of privacy.
For such offenses, society's expectation has been that law enforcement
agents and others would not—and indeed, in the main, simply could not
—secretly monitor and catalogue every single movement of an
individual's car for a very long period. In this case, for four weeks,
law enforcement agents tracked every movement that respondent made in
the vehicle he was driving. We need not identify with precision the
point at which the tracking of this vehicle became a search, for the
line was surely crossed before the 4-week mark. Other cases may
present more difficult questions. But where uncertainty exists with
respect to whether a certain period of GPS surveil
lance is long enough to constitute a Fourth Amendment search, the
police may always seek a warrant.19 We also need not consider whether
prolonged GPS monitoring in the context of investigations involving
extraordinary offenses would similarly intrude on a constitutionally
protected sphere of privacy. In such cases, long-term tracking might
have been mounted using previously available techniques.
* * *
For these reasons, I conclude that the lengthy monitoring that
occurred in this case constituted a search under the Fourth Amendment.
I therefore agree with the majority that the decision of the Court of
Appeals must be affirmed.
1. In this litigation, the Government has conceded
noncompliance with the warrant and has argued only that a warrant was
not required. United States v. Maynard, 615 F. 3d 544, 566, n. (CADC
2.As we have noted, the Jeep was registered to Jones's wife.
The Government acknowledged, however, that Jones was "the exclusive
driver." Id., at 555, n. (internal quotation marks omitted). If Jones
was not the owner he had at least the property rights of a bailee. The
Court of Appeals concluded that the vehicle's registration did not
affect his ability to make a Fourth Amendment objection, ibid., and
the Government has not challenged that determination here. We
therefore do not consider the Fourth Amendment significance of Jones's
3. JUSTICE ALITO's concurrence (hereinafter concurrence)
doubts the wisdom of our approach because "it is almost impossible to
think of late-18th-century situations that are analogous to what took
place in this case." Post, at 3 (opinion concurring in judgment). But
in fact it posits a situation that is not far afield—a constable's
concealing himself in the target's coach in order to track its
movements. Ibid. There is no doubt that the information gained by that
trespassory activity would be the product of an unlawful search—
whether that information consisted of the conversations occurring in
the coach, or of the destinations to which the coach traveled.
In any case, it is quite irrelevant whether there was an
18th-century analog. Whatever new methods of investigation may be
devised, our task, at a minimum, is to decide whether the action in
question would have constituted a "search" within the original meaning
of the Fourth Amendment. Where, as here, the Government obtains
information by physically intruding on a constitutionally protected
area, such a search has undoubtedly occurred.
4. Thus, the concurrence's attempt to recast Alderman as
meaning that individuals have a "legitimate expectation of privacy in
all conversations that [take] place under their roof," post, at 6-7,
is foreclosed by the Court's opinion. The Court took as a given that
the homeowner's "conversational privacy" had not been violated.
5.The concurrence notes that post-Katz we have explained that
" 'an actual trespass is neither necessary nor sufficient to establish
a constitutional violation.' " Post, at 6 (quoting United States v.
Karo, 468 U. S. 705, 713 (1984)). That is undoubtedly true, and
undoubtedly irrelevant. Karo was considering whether a seizure
occurred, and as the concurrence explains, a seizure of property
occurs, not when there is a trespass, but "when there is some
meaningful interference with an individual's possessory interests in
that property." Post, at 2 (internal quotation marks omitted).
Likewise with a search. Trespass alone does not qualify, but there
must be conjoined with that what was present here: an attempt to find
something or to obtain information.
Related to this, and similarly irrelevant, is the
concurrence's point that, if analyzed separately, neither the
installation of the device nor its use would constitute a Fourth
Amendment search. See ibid. Of course not. A trespass on "houses" or
"effects," or a Katz invasion of privacy, is not alone a search unless
it is done to obtain information; and the obtaining of information is
not alone a search unless it is achieved by such a trespass or
invasion of privacy.
6. Knotts noted the "limited use which the government made of
the signals from this particular beeper," 460 U. S., at 284; and
reserved the question whether "different constitutional principles may
be applicable" to "dragnet-type law enforcement practices" of the type
that GPS tracking made possible here, ibid.
7. The Government also points to Cardwell v. Lewis, 417 U. S.
583 (1974), in which the Court rejected the claim that the inspection
of an impounded vehicle's tire tread and the collection of paint
scrapings from its exterior violated the Fourth Amendment. Whether the
plurality said so because no search occurred or because the search was
reasonable is unclear. Compare id., at 591 (opinion of Blackmun, J.)
("[W]e fail to comprehend what expectation of privacy was infringed"),
with id., at 592 ("Under circumstances such as these, where probable
cause exists, a warrantless examination of the exterior of a car is
not unreasonable . . . ").
8. Thus, our theory is not that the Fourth Amendment is
concerned with "any technical trespass that led to the gathering of
evidence." Post, at 3 (ALITO, J., concurring in judgment) (emphasis
added). The Fourth Amendment protects against trespassory searches
only with regard to those items ("persons, houses, papers, and
effects") that it enumerates. The trespass that occurred in Oliver may
properly be understood as a "search," but not one "in the
constitutional sense." 466 U. S., at 170, 183.
*. United States v. Knotts, 460 U. S. 276 (1983), does not
foreclose the conclusion that GPS monitoring, in the absence of a
physical intrusion, is a Fourth Amendment search. As the majority's
opinion notes, Knotts reserved the question whether " 'different
constitutional principles may be applicable' " to invasive law
enforcement practices such as GPS tracking. See ante, at 8, n. 6
(quoting 460 U. S., at 284).
United States v. Karo, 468 U. S. 705 (1984), addressed the
Fourth Amendment implications of the installation of a beeper in a
container with the consent of the container's original owner, who was
aware that the beeper would be used for surveillance purposes. Id., at
707. Owners of GPS-equipped cars and smartphones do not contemplate
that these devices will be used to enable covert surveillance of their
movements. To the contrary, subscribers of one such service greeted a
similar suggestion with anger. Quain, Changes to OnStar's Privacy
Terms Rile Some Users, N. Y. Times (Sept. 22, 2011), online at
privacy-terms-rile-some-users (as visited Jan. 19, 2012, and available
in Clerk of Court's case file). In addition, the bugged container in
Karo lacked the close relationship with the target that a car shares
with its owner. The bugged container in Karo was stationary for much
of the Government's surveillance. See 468 U. S., at 708—710. A car's
movements, by contrast, are its owner's movements.
91Although the record does not reveal the size or weight of
the device used in this case, there is now a device in use that weighs
two ounces and is the size of a credit card. Tr. of Oral Arg. 27.
10. At common law, a suit for trespass to chattels could be
maintained if there was a violation of "the dignitary interest in the
inviolability of chattels," but today there must be "some actual
damage to the chattel before the action can be maintained." W. Keeton,
D. Dobbs, R. Keeton, & D. Owen, Prosser & Keeton on Law of Torts 87
(5th ed. 1984) (hereinafter Prosser & Keeton). Here, there was no
actual damage to the vehicle to which the GPS device was attached.
11. The Court suggests that something like this might have
occurred in 1791, but this would have required either a gigantic
coach, a very tiny constable, or both—not to mention a constable with
incredible fortitude and patience.
12.See, e.g., Cal. Family Code Ann. §760 (West 2004).
13.See Uniform Marital Property Act §4, 9A U. L. A. 116
14.See, e.g., NPR, The End of Privacy
http://www.npr.org/series/ 114250076/the-end-of-privacy (all Internet
materials as visited Jan. 20, 2012, and available in Clerk of Court's
case file); Time Magazine, Everything About You Is Being Tracked—Get
Over It, Joel Stein, Mar. 21, 2011, Vol. 177, No. 11.
15. See Kerr, The Fourth Amendment and New Technologies:
Constitutional Myths and the Case for Caution, 102 Mich. L. Rev. 801,
850-851 (2004) (hereinafter Kerr).
16.See CTIA Consumer Info, 50 Wireless Quick Facts,
17.See, e.g., The bright side of sitting in traffic:
Crowdsourcing road congestion data, Google Blog,
18.Even with a radio transmitter like those used in United
States v. Knotts, 460 U. S. 276 (1983), or United States v. Karo, 468
U. S. 705 (1984), such long-term surveillance would have been
exceptionally demanding. The beepers used in those cases merely "emit
[ted] periodic signals that [could] be picked up by a radio receiver."
Knotts, 460 U.S., at 277. The signal had a limited range and could be
lost if the police did not stay close enough. Indeed, in Knotts
itself, officers lost the signal from the beeper, and only "with the
assistance of a monitoring device located in a helicopter [was] the
approximate location of the signal . . . picked up again about one
hour later." Id., at 278.
19.In this case, the agents obtained a warrant, but they did
not comply with two of the warrant's restrictions: They did not
install the GPS device within the 10-day period required by the terms
of the warrant and by Fed. Rule Crim. Proc. 41(e)(2)(B)(i), and they
did not install the GPS device within the District of Columbia, as
required by the terms of the warrant and by 18 U. S. C. §3117(a) and
Rule 41(b)(4). In the courts below the Government did not argue, and
has not argued here, that the Fourth Amendment does not impose these
precise restrictions and that the violation of these restrictions does
not demand the suppression of evidence obtained using the tracking
device. See, e.g., United States v. Gerber, 994 F. 2d 1556, 1559-1560
(CA11 1993); United States v. Burke, 517 F. 2d 377, 386-387 (CA2
1975). Because it was not raised, that question is not before us.