Law Enforcement Use of Global Positioning
(GPS) Devices to Monitor Motor Vehicles:
Fourth Amendment Considerations
Alison M. Smith
Legislative Attorney
November 22, 2011
Congressional Research Service
7-5700
www.crs.gov
R41663
CRS Report for Congress
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epared for Members and Committees of Congress
Law Enforcement Use of GPS Devices to Monitor Motor Vehicles
Summary
As technology continues to advance, what was once thought novel, even a luxury, quickly
becomes commonplace, even a necessity. Global Positioning System (GPS) technology is one
such example. Generally, GPS is a satellite-based technology that discloses the location of a given
object. This technology is used in automobiles and cell phones to provide individual drivers with
directional assistance. Just as individuals are finding increasing applications for GPS technology,
state and federal governments are as well. State and federal law enforcement use various forms of
GPS technology to obtain evidence in criminal investigations. For example, federal prosecutors
have used information from cellular phone service providers that allows real-time tracking of the
locations of customers’ cellular phones. Title III of the Omnibus Crime Control and Safe Streets
Act of 1958 (P.L. 90-351) regulates the interception of wire, oral, and electronic communications.
As such, it does not regulate the use of GPS technology affixed to vehicles and is beyond the
scope of this report. However, bills introduced in the 112th Congress, such as S. 1212 and H.R.
2168, would address circumstances under which law enforcement may obtain, use, or disclose
GPS data.
The increased reliance on GPS technology raises important societal and legal considerations.
Some contend that law enforcement’s use of such technology to track motor vehicles’ movements
provides for a safer society. Conversely, others have voiced concerns that GPS technology could
be used to reveal information inherently private. Defendants on both the state and federal levels
are raising Fourth Amendment constitutional challenges, asking the courts to require law
enforcement to first obtain a warrant before using GPS technology.
Subject to a few exceptions, the Fourth Amendment of the U.S. Constitution requires law
enforcement to obtain a warrant before conducting a search or making a seizure. Courts continue
to grapple with the specific issue of whether law enforcement’s use of GPS technology constitutes
a search or seizure, as well as the broader question of how the Constitution should address
advancing technology in general. The Supreme Court may provide some answers in United States
v. Jones (131 S.Ct. 3064 (2011)) when it addresses the issue of whether law enforcement’s use of
GPS technology in connection with motor vehicles falls within the Fourth Amendment’s purview.
Lower federal courts have arrived at varying conclusions. Several district and circuit courts of
appeals have concluded that law enforcement’s current use of GPS technology does not constitute
a search, and is thus permissible, under the Constitution. One circuit court has found the duration
of GPS tracking to be constitutionally significant. State legislatures and state courts have
approached the issue in various ways. Some states have enacted laws requiring law enforcement
to obtain a warrant before using GPS technology. Some state courts have resolved the question
under their own constitutions. Other state courts have relied on Supreme Court precedent, such as
United States v. Knotts, 460 U.S. 276 (1983), to derive an answer.
This report discusses the basics of GPS technology, society’s reliance on it, and some of the
related legal and privacy implications. In addition, the report examines legislative and judicial
responses on both federal and state levels.
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Law Enforcement Use of GPS Devices to Monitor Motor Vehicles
Contents
Global Positioning System (GPS) Technology................................................................................ 1
Law Enforcement’s Uses of GPS Technology........................................................................... 1
The Fourth Amendment ................................................................................................................... 3
The Fourth Amendment and Technology .................................................................................. 5
GPS Monitoring: States’ Responses ................................................................................................ 7
GPS Monitoring: Federal Courts ..................................................................................................... 8
Differing Decisions........................................................................................................................ 10
Competing Interests ....................................................................................................................... 10
Conclusion ..................................................................................................................................... 12
Contacts
Author Contact Information........................................................................................................... 12
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Law Enforcement Use of GPS Devices to Monitor Motor Vehicles
Global Positioning System (GPS) Technology
GPS “is a satellite-based technology that reveals information about the location, speed, and
direction of a targeted subject. While it was initially developed for the U.S. military, countless
civilian applications of GPS appear in the marketplace.”1 For example, many people rely on an
automotive GPS device when they travel2 for navigational directions, or even to find dining
options. Similarly, some companies equip their vehicles with built-in GPS devices that allow a
command center to know a vehicle’s location upon its involvement in an accident or track it if it
is stolen.3 Pet collars have been outfitted with GPS devices to enable owners to locate their lost
pets.4 Campers and hikers use portable GPS devices to determine their location and map out their
journey.5 Cellular phones are embedded with GPS devices to synchronize time changes when a
person leaves a certain time zone.6 Cartographers use GPS devices to make maps and surveyors
to determine property boundaries.7 Airlines use them to pilot and locate planes.8 In short, not only
are Americans finding an increased interest in GPS technology, but it is becoming an essential
aspect of many Americans’ day-to-day lives.9
Law Enforcement’s Uses of GPS Technology
The military and private sector are not alone in their interests and reliance on GPS technology.
Federal and state governments have also incorporated it into many of their domestic activities.
Examples include tracking stranded motorists and predicting natural disasters such as
earthquakes, tsunamis, hurricanes, etc. Such tracking allows for more effective emergency
preparedness and relief to victims.10
Increasingly, law enforcement relies on and finds new uses for GPS technology to assist in
monitoring and gathering evidence.11 For example, sex offenders are outfitted with ankle
1 Renee McDonald Hutchins, Tied Up in Knotts? GPS Technology and the Fourth Amendment, 55 UCLA L. Rev. 409,
414 (2007); see also the Global Positioning System, http://www.gps.gov.
2 See Global Positioning System, Roads & Highways, http://www.gps.gov/applications/roads. One brand name
example is a TomTom. The individual can enter into the device an address, and an automated voice, along with
interactive maps, will guide the driver. See TomTom, How Does GPS Work?, http://www.tomtom.com/
howdoesitwork/index.php?Language=1.
3 See, e.g., OnStar, Our Privacy Practices, Effective January 1, 2011, https://www.onstar.com/web/portal/
privacy#Header . OnStar provides other limited circumstances when it will track the location of the vehicle, such as an
in-car request for service, or when OnStar needs to conduct research or troubleshooting, it is delivering enhanced
services, it is protecting its rights or the safety of the owner or others, or it is required to by law. Id.
4 Adam Koppel, Note, Warranting a Warrant: Fourth Amendment Concerns Raised by Law Enforcement’s Warrantless
Use of GPS and Cellular Tracking, 64 U. Miami L. Rev. 1061, 1064 (2010).
5 Joyce Priddy, Different Uses of GPS Devices, associatedcontent.com, (September 22, 2007),
http://www.associatedcontent.com/article/389315/different_uses_of_gps_devices.html?cat=15; see also the Global
Positioning System, Recreation, http://www.gps.gov/applications/recreation.
6 The Global Positioning System, Timing, http://www.gps.gov/applications/timing.
7 The Global Positioning System, Surveying & Mapping, http://www.gps.gov/applications/survey.
8 The Global Positioning System, Aviation, http://www.gps.gov/applications/aviation.
9 Koppel, supra note 4, at 1064 (providing statistics on the growing trends in GPS technology).
10 The Global Positioning System, Public Safety & Disaster Relief, http://www.gps.gov/applications/safety.
11 To illustrate the government’s growing use of GPS technology in the area of criminal investigation, consider that
“[i]n response to a Freedom of Information Act request, police in one Virginia locality reported that they used GPS
(continued...)
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monitors to track their movements 24 hours a day. Also, consider the following examples, taken
by various state law enforcement authorities:
• After 11 attacks on women were reported during a six-month period in two
Virginia counties, police installed a GPS device on the van owned by a man who
lived near the crime scenes. The suspect was a convicted rapist who had served
17 years in prison. By tracking his movements with the device, police were able
to intercept him in Falls Church, VA, where he was dragging a woman to a
remote area. The series of assaults ceased after his arrest.12
• Wisconsin police, acting on a tip about a former methamphetamine manufacturer,
attached a GPS device to the suspect’s car without first obtaining a warrant.
Information recorded on the device led them to a large tract of land visited by the
suspect. With the consent of the landowner, they searched the property and found
paraphernalia used to manufacture methamphetamines. The suspect was
subsequently arrested.13
• Police in New York used evidence acquired from a GPS device (attached without
first obtaining a warrant) that had been attached to a burglary suspect’s car a year
earlier. The device, which monitored the suspect’s movement without
interruption for more than two months, showed that the suspect had driven by a
burglarized store. This evidence was used to corroborate a witness’s testimony
that the suspect had been observing the store to determine its vulnerable points.14
• In California, the Los Angeles Police Department “outfit[ted] its cruisers with air
guns that can launch GPS-enabled ‘darts’ at passing cars.”15 Once affixed to a
vehicle, police can track it in real time from police headquarters. The air guns are
generally used in situations requiring immediate action such as a high-speed
chase.16
Most new cellular phones include GPS capabilities.17 As a result, federal prosecutors have been
known to get information from cellular phone service providers that allows real time tracking of
the locations of customers’ cellular phones.18 In one case, information obtained from a cellular
(...continued)
devices in nearly 160 cases from 2005 to 2007.” Id.
12 Ben Hubbard, Police Turn to Secret Weapon: GPS Device, Wash. Post, A1 (August 13, 2008), available at
http://www.washingtonpost.com/wpdyn/content/article/2008/08/12/AR2008081203275.html?nav=rss_metro/va; see
also Ramya Shah, From Beepers to GPS: Can the Fourth Amendment Keep Up with Electronic Tracking Technology?,
2009 U. Ill. J.L. Tech. & Pol’y 281, 281 (Spring 2009) (providing an example of law enforcement’s use of a GPS
device to tie a suspect to the murder).
13 United States v. Garcia, 474 F.3d 994, 995 (7th Cir. 2007).
14 People v. Weaver, 909 N.E.2d 1195, 1195-96 (N.Y. 2009).
15 Hutchins, supra note 1, at 418-19. The darts consist of a miniaturized GPS receiver, radio transmitter, and battery
embedded in a sticky compound material.
16 Id. at 419-20 (internal citations omitted).
17 Id. at 419. Title III of the Omnibus Crime Control and Safe Streets Act of 1958 (P.L. 90-351) regulates the
interception of wire, oral, and electronic communications. As such, it does not regulate the use of GPS technology
affixed to vehicles and is beyond the scope of this report. For a discussion of wiretapping or electronic eavesdropping,
refer to CRS Report 98-326, Privacy: An Overview of Federal Statutes Governing Wiretapping and Electronic
Eavesdropping, by Gina Stevens and Charles Doyle.
18 Michael Isikoff, The Snitch in Your Pocket, Newsweek (February 19, 2010), http://www.newsweek.com/2010/02/18/
(continued...)
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phone’s GPS helped prove that a key suspect had been within a mile of a murder scene. In
another case, a Mexican drug-cartel truck was tracked. The truck was carrying over two tons of
cocaine.19
While there are many substantial benefits to the use of GPS technology, some have voiced
concerns. Many of these concerns arise from law enforcement’s use of GPS technology without
first obtaining a warrant to either attach the device or monitor the suspect after the device has
been attached. Some have argued that the warrantless use of GPS technology has the potential of
interfering with individual privacy, protected by the Fourth Amendment to the United States
Constitution.20 Legal scholars assert that a warrant ensures that the police have probable cause to
believe that criminal activity is taking place or is imminent, thus preventing unwarranted
intrusion into a person’s freedom and private life.21 Others contend that GPS tracking is
analogous to law enforcement conducting public surveillance with its own eyes or with
surveillance cameras or radio transmitting beepers. Therefore, some courts and legal scholars
believe a warrant is unnecessary and the Fourth Amendment does not apply.22
The Fourth Amendment
The Fourth Amendment to the United States Constitution, which protects “[t]he right of the
people to be secure ... against unreasonable searches and seizures,”23 governs and circumscribes
searches and seizures24 made by the federal and the state governments.25 The Amendment’s
operative text can be divided into two clauses. The first clause forbids the government from
conducting any search or seizure that is “unreasonable.” The second clause prohibits the
government from issuing a warrant unless it is obtained based “upon probable cause,” is
“supported by Oath,” and contains particularized descriptions of the “place to be searched” and
(...continued)
the-snitch-in-your-pocket.html.
19 Id.
20 Almost 50 years ago, in Lopez v. United States, 373 U.S. 427, 442 (1963), Chief Justice Warren remarked:
That the fantastic advances in the field of electronic communication constitute a great danger to the
privacy of an individual; that indiscriminate use of such devices in law enforcement raises grave
constitutional questions under the Fourth and Fifth Amendment;…”
21 See, e.g., Hutchins, supra note 1, at 464-65; Koppel, supra note 4, at 1089; Maynard, 615 F.3d at 564; Weaver, 909
N.E.2d at 1201-02; Kip F. Wainscott, Unwarranted Intrusion: GPS and the Fourth Amendment, ACSblog (May 19,
2009, 11:52 AM), http://acslaw.org/node/13444?gclid=CLD254CK56QCFeFM5QodvBbU2A.
22 See, e.g., Pineda-Moreno, 591 F.3d at 1214-16; Tarik N. Jallad, Recent Development, Old Answers to New
Questions: GPS Surveillance and the Unwarranted Need for Warrants, 11 N.C. J. L. & Tech. 351, 374-75 (Spring
2010); Orin Kerr, Does the Fourth Amendment Prohibit Warrantless GPS Surveillance?, The Volokh Conspiracy (Dec.
13, 2009), http://volokh.com/2009/12/13/does-the-fourth-amendment-prohibit-warrantless-gps-surveillance/.
23 “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.
24 This protection even includes searches and seizures conducted “beyond the sphere of criminal investigations.” City of
Ontario v. Quon, 130 S.Ct. 2619, 2627 (2010).
25 Although the Fourth Amendment, like the Fifth Amendment, was originally understood to apply only to federal
government action, see Barron v. City of Baltimore, 32 U.S. 243, 247-51 (1833), the Supreme Court later found that it
became applicable to the states through the Due Process Clause of the Fourteenth Amendment. Mapp v. Ohio, 367 U.S.
643, 660 (1961).
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what is “to be seized.” Although “[t]here is nothing in the amendment’s text to suggest that a
warrant is required to make a search or seizure reasonable,”26 the U.S. Supreme Court has long
since read these two clauses together, generally holding that a warrantless search or seizure is
presumptively (if not per se) unreasonable.27 The Fourth Amendment does not apply, however,
unless the government’s conduct constitutes a search or seizure within the meaning of the
Amendment, that is, where there is a justifiable expectation of privacy. In addition, even when the
Amendment does apply, “because the ultimate touchstone of the Fourth Amendment is
‘reasonableness,’ the warrant requirement is subject to certain exceptions.”28
At one time, the purpose of the Fourth Amendment was seen as a protection of people’s property
rights against unlawful physical trespasses.29 However, it gradually came to be seen as a
protection of something more.30 “[T]he principal object of the Fourth Amendment,” the Court has
explained, “is the protection of privacy rather than property.”31 In addition, “the Fourth
Amendment protects people—and not simply ‘areas’—against unreasonable searches and
seizures.”32 Thus, in its seminal decision in Katz v. United States,33 the Court held that police
officers violated the Fourth Amendment when they conducted a warrantless search using a
listening and recording device placed on the outside of a public phone booth to eavesdrop on the
conversation of a suspect who had “‘justifiably relied’ upon ... [the privacy of the] telephone
booth.”34 The Court concluded that the Fourth Amendment protects both a person and that
person’s expectation of privacy from warrantless searches or seizures in places which are
justifiably believed to be private.
It is not enough, however, for a person to have a subjective “expectation of privacy,” for any
person might claim that she expected privacy at any time and in any place. Indeed, many might
argue that the police conduct a search by simply watching them. Therefore, they will reason,
because the police did not have a warrant, they violated the Constitution and the evidence
obtained cannot be used against them.35 However, the Court has rejected such broad
26 Garcia, 474 F.3d at 996.
27 See, e.g., City of Ontario, 130 S.Ct. at 2630; Brigham City v. Stuart, 547 U.S. 398, 403 (2006); Groh v. Ramirez, 540
U.S. 551, 559 (2004); United States v. Ross, 456 U.S. 798, 824-25 (1982); Mincey v. Arizona, 437 U.S. 385, 390
(1978); Katz v. United States, 389 U.S. 347, 357 (1967). The Court has gone back and forth on whether warrantless
searches or seizures are presumptively unreasonable or per se unreasonable. It is unclear which approach the Court
currently follows.
28 Brigham City, 547 U.S. at 403. As the Court in Brigham City outlined, some of these exceptions include law
enforcement’s engaging “in hot pursuit of a fleeing suspect,” preventing “the imminent destruction of evidence,”
extinguishing a fire on private property and investigating its cause, or assisting “persons who are seriously injured or
threatened with such injury.” Id. (internal quotations and citations omitted).
29 See, e.g., Boyd v. United States, 116 U.S. 616, 627 (1886); Adams v. New York, 192 U.S. 585, 598 (1904); Olmstead
v. United States, 277 U.S. 438, 464-66 (1928); Goldman v. United States, 316 U.S. 129, 134-36 (1942); see also Kyllo
v. United States, 533 U.S. 27, 31-33 (2001) (discussing the historical evolving emphasis of Fourth Amendment
protection).
30 See, e.g., Silverthorne Lumber Co. v. United States, 251 U.S. 385 (1920); Jones v. United States, 362 U.S. 257, 266
(1960), overruled on other grounds by United States v. Salvucci, 448 U.S. 83 (1980); Silverman v. United States, 365
U.S. 505, 511-12 (1961); Warden v. Hayden, 387 U.S. 294, 304 (1967); Rakas v. Illinois, 439 U.S. 128, 143 (1986).
31 Warden, 387 U.S. at 304-05 (discussing the shift of emphasis from property to privacy).
32 Katz, 389 U.S. at 353. This focus finds support in the Amendment’s text, which begins by stating that it protects
“[t]he right of the people.” U.S. Const. amend. IV.
33 389 U.S. 347 (1967).
34 Kyllo, 533 U.S. at 33 (quoting Katz, 389 U.S. at 353).
35 The Fourth Amendment’s mandates are enforced through the application of an exclusionary rule which generally
(continued...)
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interpretations of the term “search,” holding instead “that visual observation is no ‘search’ at
all.”36 Simply put, “the police cannot reasonably be expected to avert their eyes from ... activity
that could have been observed by any member of the public. Hence, ‘[w]hat a person knowingly
exposes to the public, even in his own home or office, is not a subject of Fourth Amendment
protection.’”37
In applying the principles set forth in Katz to determine whether law enforcement has conducted a
search or a seizure within the meaning of the Fourth Amendment, the Court frequently cites
Katz’s concurring opinion. The concurring opinion clarified the Court’s test as being “whether a
person has a ‘constitutionally protected reasonable expectation of privacy.’”38 Courts presently
examine law enforcement’s conduct to make this threshold determination by following “a two-
part inquiry: first, has the individual manifested a subjective expectation of privacy in the object
of the challenged search? Second, is society willing to recognize that expectation as
reasonable?”39
The Fourth Amendment and Technology
State and federal courts have long since wrestled with whether and how to apply the Katz test to
advancing technology. For example, the Supreme Court in Katz determined that when the suspect
entered the phone booth and shut the door, he had a reasonable expectation of privacy that his
telephone conversation would be private. Thus, the police conducted an unreasonable search by
using a listening and recording device without getting a warrant. Similarly, in Kyllo v. United
States,40 the Court decided that a suspect had a reasonable expectation of privacy in his home
when the police, suspecting him of growing marijuana, used a thermal imaging device without a
warrant to detect the heat emanating from it. In contrast, when the Court was asked in United
States v. Ciraolo41 to decide whether a suspect had a reasonable expectation of privacy in a back
yard he surrounded with a 10-foot-high fence, the Court concluded that police observation from
an airplane in public air space was not a search; thus, no warrant was necessary.
(...continued)
states that evidence illegally seized may not be used against the defendant. See, Weeks v. United States, 232 U.S. 383
(1914) (holding that the Fourth Amendment barred the use of evidence secured through a warrantless search); Mapp v.
Ohio, 367 U.S. 643 (1961) (holding that the exclusionary rule applies to the states).
36Kyllo, 533 U.S. at 32. “A search,” the Court has explained, “comprises the individual interest in privacy; a seizure
deprives the individual of dominion over his or her [person or] personal property.” Horton v. California, 496 U.S. 128,
133 (1990). The use of a GPS to conduct surveillance would seem to fall under the rubric of a search; the attachment of
a GPS device lends itself more to the concept of a seizure. See United States v. Karo, 468 U.S. 705, 712-13 (1984)
(recognizing the difference in issues raised by the two concepts).
37 California v. Greenwood, 486 U.S. 35, 40-41 (1988).
38 United States v. Ciraolo, 476 U.S. 207, 211 (1986) (quoting Katz v. United States, 389 U.S. 347, 360 (1967) (Harlan,
J., concurring)); see also Kyllo, 533 U.S. at 33-34.
39 Ciraolo, 476 U.S. at 211; see also Kyllo, 533 U.S. at 34.
40 533 U.S. 27, 34 (2001).
41 476 U.S. 207, 213-15 (1986).
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Likewise, the Court found that a defendant did not have a reasonable expectation of privacy in his
car while traveling along public roads. In United States v. Knotts,42 Minnesota law enforcement
officers placed (with the seller’s consent) a beeper in a chloroform container, believing that the
defendant buyer was engaging in the production of illicit drugs. Officers subsequently followed
the vehicle carrying the container, maintaining both a visual surveillance and a monitor receiving
the beeper signals. Based on the beeper signals, the officers tracked the container to the
defendant’s secluded cabin. After a three-day visual surveillance of the cabin, the officers
obtained and executed a search warrant and found the container and a drug laboratory in the
cabin. The defendant sought to have the evidence suppressed, arguing that the warrantless
monitoring of the beeper violated the Fourth Amendment.
The Court disagreed and held that the officers’ actions did not constitute a search or seizure, as
the defendant did not have a legitimate expectation of privacy. The beeper signal was not used to
monitor movement of the container within a private residence. Instead, it was used to monitor
movement along public highways and other areas visible to the naked eye.
However, in a similar scenario, when a beeper was activated while inside various suspects’
homes, the Court held that suspects with interests in those respective homes did have a reasonable
expectation of privacy and that the absence of a warrant constituted an unreasonable search.43 In
United States v. Karo,44 Drug Enforcement Administration (DEA) agents installed an electronic
beeper in a can of ether with the consent of the owner (a government informant). The marked can
was sold with others to the defendants, who intended to use the contents for cocaine production.
Having tracked the can to several residences and storage facilities, law enforcement determined
the can’s location and obtained an arrest warrant. The defendants were arrested and charged with
possession of cocaine with intent to distribute. One of the defendants sought to have the evidence
suppressed as “tainted fruit” of an unlawful search. This case presented two issues for the Court
to address: (1) whether the beeper’s installation constituted a search or seizure when the container
was delivered to a buyer without any knowledge of the beeper’s presence and (2) whether the
beeper’s monitoring within an individual’s residence falls within the Fourth Amendment’s ambit
when it reveals information that could not have been obtained through visual surveillance.
As to the first issue, the Court found that the defendant lacked a Fourth Amendment interest, as
the then-owner’s consent was sufficient to withstand the challenge. 45 However, the Court found
that the Fourth Amendment was violated when the agents used the beeper to locate the container
in a private dwelling without first obtaining a search warrant. Although the transfer of the beeper
to the defendant did not violate the Fourth Amendment, the monitoring of the beeper in a private
residence not open to visual surveillance did violate the Fourth Amendment.46
42 460 U.S. 276, 281-84 (1983).
43 However, the Court found that the arrest warrant was valid, as it was based on an affidavit, which contained a
significant amount of evidence from sources other than the beeper.
44 468 U.S. 705, 713-16 (1984).
45 But see, 468 U.S. at 729-30 (Stevens, J., dissenting)(stating that the beeper’s attachment constituted a “seizure.”).
46 The Court declined to decide whether a search warrant to monitor a beeper would require probable cause or
reasonable suspicion.
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GPS Monitoring: States’ Responses
States have employed various approaches toward the use of GPS technology. Some states have
addressed the issue statutorily by enacting laws “imposing civil and criminal penalties for the
[improper] use of electronic tracking devices or expressly requiring exclusion of evidence
produced by such a device unless obtained by the police acting pursuant to a warrant.”47
Judicially, state courts have reached differing conclusions. State courts in New York, Washington,
Oregon, Delaware, and Massachusetts have determined that, absent some exigent circumstance,
police officers must first obtain a warrant before using GPS technology (in some cases the court
is interpreting its respective state constitution).48 For example, in State v. Weaver,49 the Court of
Appeals of New York held that the “unconsented placement” of a GPS tracking device and
subsequent monitoring of the vehicle constituted a search requiring a warrant under the state’s
constitution.50 The court noted that it has interpreted its constitution to provide greater protections
than the Fourth Amendment “in the areas of search and seizure.”51 The court found that the
defendant had a reasonable expectation of privacy that was infringed by the state’s action. While
the court found that the defendant had a diminished expectation of privacy, “that expectation was
not reduced to zero.”
Conversely, state courts in Nevada and Virginia have found that GPS use does not raise any state
or federal constitutional concerns.52 In Foltz v. Commonwealth,53 the Virginia court found that the
law enforcement’s use of a GPS tracking device to track a vehicle’s movement on a public street
did not constitute a search or seizure under either the federal or state constitutions. The defendant,
a registered sex offender on probation for committing sexual assault, became a suspect in a new
series of sexual assaults. Police attached a GPS device to the defendant’s work vehicle. Observing
“in real time via a computer screen with a map,”54 police noticed that the van was driven in and
out of various neighborhoods where crimes had occurred. After another sexual assault occurred,
the police followed the defendant the next day and witnessed him grab a woman and knock her
down to the ground. The police stopped the assault and arrested the defendant. In reaching its
decision, the court concluded that the defendant did not manifest a subjective expectation of
privacy while driving down the street looking for victims. Moreover, the court concluded that the
defendant “did nothing to prevent others from inspecting the bumper of the work van.” Many
47 United States v. Maynard, 615 F.3d 544, 564 (D.C. Cir. 2010)(listing several states and the relevant legislation in
each). See, e.g., Utah Code Ann. §§ 77-23a-4, 77-23a-7, 77-23a-15.5; Minn. Stat. §§ 626A.37, 626A.35; Fla. Stat. §§
934.06, 934.42; S.C.Code Ann. § 17-30-140; Okla. Stat., tit. 13, §§ 176.6, 177.6; Haw. Rev. Stat. §§ 803-42, 803-44.7;
18 Pa. Cons.Stat. § 5761.
48 See State v. Weaver, 909 N.E.2d 1195 (N.Y. 2009) (GPS use, under state constitution, is unconstitutional without a
warrant); State v. Jackson, 76 P.3d 217 (Wash. 2003); State v. Campbell, 759 P.2d 1040 (Or. 1988); Delaware v.
Biddle, No. CRIM.A. 05-01-1052, 2005 WL 3073593, at *1 (Del. Com. Pl. May 5, 2005); see also Commonwealth v.
Connolly, 913 N.E.2d 356 (Mass. 2009) (installation of a GPS device was a seizure).
49 909 N.E.2d 1195 ( N.Y. 2009).
50 Id. at 1202.
51 Id.
52 See Osburn v. State, 44 P.3d 523 (Nev. 2002); Foltz v. Commonwealth, 698 S.E.2d 281 (Va. Ct. App. 2010), reh’g en
banc granted and mandate stayed by 699 S.E. 2d 522 (Va. Ct. App. 2010).
53 698 S.E.3d 281 (Va. Ct. App. 2010), reh’g en banc granted and mandate stayed by 699 S.E. 2d 522 (Va. Ct. App.
2010).
54 Id. at 286.
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states have not addressed the issue of GPS tracking either legislatively or judicially as of this
writing.
GPS Monitoring: Federal Courts
The Supreme Court has not directly addressed the issue of whether law enforcement’s use of GPS
technology in connection with motor vehicles falls within the Fourth Amendment’s purview.
Lower federal courts have relied on Supreme Court precedent on other types of monitoring to
arrive at arguably varying conclusions on GPS tracking.
Several district and circuit courts of appeals have concluded that law enforcement’s current use of
GPS technology does not constitute a search and is thus permissible under the Constitution.55 For
example, in United States v. Pineda-Moreno,56 the 9th Circuit decided a case involving a criminal
drug investigation in Oregon. Without a warrant, DEA agents attached a GPS device to a Jeep
owned by a man suspected of drug activity. The device was attached on several occasions over a
four-month period.57 Four times agents attached the device while the Jeep was parked on a public
street; one time while it was parked at a public parking lot; and two times while it was parked on
his property, necessitating that agents sneak onto it in the early morning hours.58 Eventually, the
GPS “device alerted agents that [the suspect’s] vehicle was leaving a suspected marijuana grow
site.” The suspect was then arrested and officers found marijuana in the Jeep.59
The court held that the DEA’s actions did not constitute a search because a person does not have a
reasonable expectation of privacy in a car’s exterior, even when the car is parked on the person’s
driveway (unless the person has affirmatively sought to exclude others from entering his land).60
The court then held that the DEA’s monitoring of the suspect’s travel was analogous to the facts
in Knotts, where the police followed the suspect’s car by using a beeper on the theory that using
the GPS device disclosed information that the police “could have obtained by following the
car.”61 The court then concluded by quoting Knotts: “‘Insofar as [Pineda-Moreno’s] complaint
appears to be simply that scientific devices such as the [tracking devices] enabled the police to be
more effective in detecting crime, it simply has no constitutional foundation. We have never
equated police efficiency with unconstitutionality and decline to do so now.’”62
Similar to Pineda-Moreno, many of the courts to follow this line of reasoning also have
analogized GPS devices to the beeper devices in Knotts. In addition, many have also included a
reservation similar to the one the Supreme Court made in Knotts. In Knotts, the defendant argued
55 See, e.g., United States v. Garcia, 474 F.3d 994 (7th Cir. 2007); United States v. Marquez, 605 F.3d 604 (8th Cir.
2010); United States v. Pineda-Moreno, 591 F.3d 1212 (9th Cir. 2010); United States v. Eberle, 993 F.Supp. 794 (D.
Mont. 1998); United States v. Moran, 349 F. Supp. 2d 425 (N.D.N.Y.2005); United States v. Burton, 698 F. Supp. 2d
1303 (N.D. Fl. 2010); United States v. Williams, 650 F. Supp. 2d 633 (W.D. KY. 2009); United States v. Jesus-Nunez,
No. 1:10-CR-00017-01, 2010 WL 2991229, at *1 (July 27, 2010).
56 591 F.3d 1212 (9th Cir. 2010).
57 Id. at 1213.
58 Id.
59 Id. at 1214.
60 Id. at 1214-15.
61 Id. at 1216.
62 Id. at 1216-17 (quoting Knotts, 460 U.S. at 284 ) (alterations in original).
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that the Court’s ruling would permit the government to conduct warrantless and unlimited
surveillance with such technology: “[I]f such dragnet type law enforcement practices as the
defendant envisions should eventually occur,” the Court responded, “there will be time enough
then to determine whether different constitutional principles may be applicable.”63 It is unclear
what this “dragnet reservation” means, and the differing outcomes in the federal circuits can be
attributed to how the courts interpret it. The 9th Circuit, quoting with approval the 7th Circuit,
stated it this way: “Should [the] government someday decide to institute programs of mass
surveillance of vehicular movements, it will be time enough to decide whether the Fourth
Amendment should be interpreted to treat such surveillance as a search.”64
Conversely, the D.C. Circuit held that law enforcement’s prolonged use of GPS technology to
track a particular vehicle does amount to a search and thus requires a warrant.65 In United States v.
Maynard,66 the court found that Knotts’s “dragnet warning” applied to an individual when the law
enforcement’s warrantless surveillance was constant and protracted, and that the reservation was
not limited to mass surveillance of multiple vehicles. In this case, the Federal Bureau of
Investigation (FBI) installed a GPS device on a vehicle to track the “movements” of a club owner
suspected of conspiracy to distribute cocaine. They monitored him “[for] 24 hours a day for 28
days as he moved among scores of places, thereby discovering the totality and pattern of his
movements from place to place to place.”67 The information was subsequently used as evidence at
trial to prove his involvement in the conspiracy.68
The court distinguished its holding from the decisions in the other circuits by noting that the rule
in Knotts was limited. Whereas the other circuits had read Knotts’s dragnet reservation to mean
“mass surveillance,” the court read it to apply as well to individual, prolonged “‘twenty-four hour
surveillance.’”69 The court also concluded that a person has a reasonable expectation of privacy in
the totality of his movements over the course of a month, which he does not actually or
constructively expose to the public, even though law enforcement could constitutionally conduct
warrantless observation of his individual movements from one place to another while in public.70
The Supreme Court granted certiorari review in this case71 raising questions as to whether and
when the warrantless use of a GPS tracking device on a motor vehicle might violate the Fourth
Amendment.
63 Knotts, 460 U.S. at 284.
64 Pineda-Moreno, 591 F.3d at 1216 n.2 (quoting Garcia, 474 F.3d at 998).
65 United States v. Maynard, 615 F.3d 544 (D.C. Cir. 2010). This was a consolidated case with two defendants, Jones
and Maynard. The D.C. Circuit Court of Appeals reversed Jones’s conviction but affirmed Maynard’s. The government
appealed Jones’s reversal. As such, the case before the Supreme Court is United States v. Jones.
66 Id.
67 Id. at 558.
68 Id. at 567.
69 Id. at 556-58 (“In short, Knotts held only that ‘[a] person traveling in an automobile on public thoroughfares has no
reasonable expectation of privacy in his movements from one place to another,’ not that such a person has no
reasonable expectation of privacy in his movements whatsoever, world without end.”).
70 Id. at 558-67.
71 The D.C. Circuit Court of Appeals reversed Jones’s conviction but affirmed Maynard’s. The government appealed
Jones’s reversal. As such, the case before the Supreme Court is United States v. Jones, 131 S.Ct. 3064 (2011).
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Differing Decisions
Reading the decisions to date, it is unclear whether there is a split in Fourth Amendment
jurisprudence over use of GPS technology as such, or the cases reflect more that differences in
the extent of GPS tracking may be constitutionally significant in determining its intrusiveness. A
few courts may go so far as to conclude that any use of GPS technology, even when attaching it,
is presumptively unreasonable unless law enforcement first obtains a valid warrant.72 Other courts
may decide that the warrantless use of GPS technology is permissible, subject to one of the
already settled warrant exceptions, such as when the suspect is fleeing and the police are engaged
in hot pursuit. The state court decisions in Washington, Oregon, and New York seem to have
adopted this approach under their own constitutions. Finally, some courts may argue, which could
be seen as an attempt to reconcile the already existing decisions, that using GPS devices for a
minimal amount of time—for a few days, perhaps—is permissible, but when the monitoring
becomes prolonged—for many days, weeks, or months—the intrusiveness reaches a point where
it becomes a search requiring a warrant.73 The state court’s decision in New York might also be
read this way, and the D.C. Circuit appears to have followed this approach.74
Competing Interests
In approaching warrantless use of GPS technology, courts confront the continued appropriateness
of a principal corollary of Fourth Amendment doctrine. Fourth Amendment protection is
premised on a reasonable expectation of privacy that society is willing to recognize. For decades,
and in a variety of circumstances, courts have held that no privacy rights attach to activities that
are visually observable to the public, such as movements along public streets. The pressure on
this principle comes from the greatly enhanced reach and efficiency of tracking technologies such
as GPS. Some contend that it would be better for legislatures rather than the courts to set the rules
on GPS policy because they can more expressly balance the competing interests of enhancing law
enforcement efficiency and protection of individual privacy.75 Others argue that the courts are
capable and equipped to do it, just as they have done reconciling the law to the usage of many
other emerging technologies.76
72 See, e.g., Connolly, 913 N.E.2d at 822.
73 This approach could be called the “Mosaic Theory.” The idea is that when GPS surveillance is prolonged, the sum of
otherwise publicly exposed activities reveals patterns that are reasonably expected to be private, thus constituting a
search, which requires a warrant . See Orin Kerr, D.C. Circuit Introduces “Mosaic Theory” of Fourth Amendment,
Holds GPS Monitoring a Fourth Amendment Search, The Volokh Conspiracy (August 6, 2010), http://volokh.com/
2010/08/06/d-c-circuit-introduces-mosaic-theory-of-fourth-amendment-holds-gps-monitoring-a-fourth-amendment-
search/. The court in Maynard used this theory and tied it to the Supreme Court’s dragnet reservation in Knotts.
However, unlike the 9th and 7th Circuits, the D.C. Circuit read it to apply when law enforcement engages in prolonged
surveillance, not just mass surveillance. Maynard, 615 F.3d at 557-63.
74 The United States petitioned for a rehearing en banc to the court’s decision in Maynard. Orin Kerr, DOJ Petitions for
Rehearing in DC Circuit “Mosaic Theory” GPS Surveillance Case, The Volokh Conspiracy (September 22, 2010),
http://volokh.com/2010/09/22/doj-petitions-for-rehearing-in-dc-circuit-mosaic-theory-gps-surveillance-case/.
75 Orin S. Kerr, The Fourth Amendment and New Technologies: Constitutional Myths and the Case for Caution, 102
Mich. L. Rev. 801, 806 (2004).
76 See generally Hutchins, supra note 1; see also Renee McDonald Hutchins, The Anatomy of a Search: Intrusiveness
and the Fourth Amendment, 44 U. Rich. L. Rev. 1185, 1189 n.22 (May 2010) (noting the current debate between
whether the legislature or the judiciary is the preferred arbiter in the area of GPS technology).
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Those who argue that law enforcement does not need to obtain a warrant to use GPS technology
contend that the many uses of GPS technology simply “enable[] the police to be more effective in
detecting crime,”77 stamping it out at its earlier stages and preventing it from even occurring.
Among others, the advantages in such technology, especially when police officers are engaged in
a high-speed chase, decrease the likelihood of endangering the public, the police, or even the
suspect from the potential hazards involved in such situations. Moreover, as already discussed,
the efficiencies of GPS technology have enabled officers to prevent one woman from being raped
and any further rapes from being committed by the suspect. Likewise, proponents of GPS use
maintain that officers have been able to prevent drug production and distribution by the respective
suspects they apprehended. GPS technology, then, can be preventive, saving lives and time; it
decreases the cost of having officers out conducting surveillance while simultaneously allowing
more places and people to be monitored and more action to be taken when criminal activity
occurs. In short, from this perspective, GPS devices make law enforcement’s job more efficient,
safer, and effective, providing for a securer and safer society. They would argue that GPS
technology functions “merely as an enhancing adjunct to the surveilling officer’s eyes,”78 and
naked eye observation does not offend the Fourth Amendment because a person does not have a
reasonable expectation of privacy in activity that any member of the public might observe. GPS
technology is merely a matter of efficiency, they conclude, and the courts “have never equated
police efficiency with unconstitutionality.”79
Conversely, proponents of requiring law enforcement to obtain judicial permission before using a
GPS device contend that efficiency, security, and safety come at some unacceptable costs.80 At
“the press of a button,” for example, a GPS device can disclose one’s activities that are
“indisputably private [in] nature,” such as “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.”81 It does not only disclose “where we go, but by easy reference [it reveals] our
associations—political, religious, amicable and amorous,” as well as “the pattern of our
professional and avocational pursuits.”82 GPS technology “is not a mere enhancement of human
sensory capacity,” because the information it can capture is potentially tantamount to, “at a
minimum, millions of additional police officers and cameras on every street lamp.”83 A person
does have a reasonable expectation of privacy from the government’s ability to obtain such
comprehensive and detailed information. The ability of the government to engage in monitoring
that exposes this type of information, some even argue, foreshadows “Orwellian images of Big
Brother secretly following your movements through the small device in your pocket”84 or car,
77 Pineda-Moreno, 591 F.3d at 1216 (quoting Knotts, 460 U.S. at 284).
78 Weaver, 909 N.E.2d at 1199.
79 Knotts, 460 U.S. at 284.
80 Some cite, for example, an Historical Review of the Constitution and Government of Pennsylvania, title page (1759)
(Arno Press reprint 1972) (stating that “[t]hose who would give up essential Liberty, to purchase a little temporary
Safety, deserve neither Liberty nor Safety”) (commonly attributed to Benjamin Franklin).
81 Weaver, 909 N.E. 2d at 1198-99.
82 Id.
83 Id.
84 Michael Isikoff, The Snitch in Your Pocket, Newsweek, February 19, 2010, available at http://www.newsweek.com/
2010/02/18/the-snitch-in-your-pocket.html; see also Pineda-Moreno, 617 F.3d 1120, 1121, 1126 (9th Cir. 2010)
(Kozinski, C.J., dissenting from the denial of rehearing en banc).
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especially when the pervasive monitoring has been prolonged and continuous—for 2885 and even
6586 days, in certain cases. Besides, they contend, unless the situation is an emergency, it is not
that onerous a burden to require the police to take a few minutes to obtain judicial approval
before they use such revealing technology.87
Conclusion
Society’s increased reliance on GPS technology raises both societal and legal considerations. Law
enforcement has found many uses for GPS technology in criminal investigations. Some of these
uses in connection with motor vehicle surveillance raise concerns over the technology’s potential
interference with privacy interests protected by the Fourth Amendment. Others have argued that
GPS technology is comparable to naked eye observation, and its advantages in impeding and
preventing criminal activity are substantial. However, others contend that balancing the privacy
and law enforcement interests is not easy in a GPS context. There are also questions as to whether
guidance of GPS use should be provided legislatively or judicially. It is important to note that the
Fourth Amendment provides a floor for protection. No matter what the state legislatures or
Congress does, the requirements of the Fourth Amendment must be met. Legislation provides two
advantages: (1) clarification for procedural distinctions between warrantless and presumptively
unreasonable searches, and (2) additional protection where reenforcement is thought necessary.
Several state legislatures have enacted legislation governing the warrantless use of GPS devices.
On the federal level, bills, such as S. 1212 and H.R. 2168, in part, delineate circumstances under
which law enforcement may use, obtain, or disclose GPS information.
The Supreme Court is poised to speak to the use of GPS monitoring in Spring 2012 in United
States v. Jones. State and lower federal courts have reached differing conclusions based on the
facts presented, U.S. Supreme Court precedent on other tracking devices, and/or state
constitutions.
Author Contact Information
Alison M. Smith
Legislative Attorney
amsmith@crs.loc.gov, 7-6054
85 Maynard, 615 F.3d at 558.
86 Weaver, 909 N.E 2d at 1195.
87 “[O]fficers in Utah can get electronic warrants in about 20 minutes. ‘It’s not that hard,’” a Utah County Sherriff
stated. Janice Peterson, Conflicting views on no-warrant GPS ruling, Daily Herald (September 5, 2010), available at
http://www.heraldextra.com/news/local/article_6d44220a-e8d1-5d0b-a072-bce72e97a835.html.
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