# Reverse Warrants and the Fourth Amendment: The Supreme Court Weighs in on Geofence Searches

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URL: https://www.frixlaw.com/law-library/documents/crs%3AR48852

## Record

- **Collection:** Congressional research report
- **Document type:** Reports
- **Published:** September 15, 2026
- **Citation:** R48852

## Text

Reverse Warrants and the Fourth Amendment:
The Supreme Court Weighs in on Geofence
Searches
Updated September 15, 2026

Congressional Research Service
https://crsreports.congress.gov
R48852

SUMMARY

Reverse Warrants and the Fourth Amendment:
The Supreme Court Weighs in on Geofence
Searches

R48852
September 15, 2026
Clay Wild
Legislative Attorney

From thermal imaging and wiretaps to Global Positioning System (GPS) tracking and various
forms of electronic eavesdropping, law enforcement’s use of emerging technologies is sometimes
in tension with constitutional privacy protections. See, e.g., Kyllo v. United States, 533 U.S. 27,
29 (2001) (“This case presents the question whether the use of a thermal-imaging device aimed at a private home from a
public street to detect relative amounts of heat within the home constitutes a ‘search’ within the meaning of the Fourth
Amendment.”); Olmstead v. United States, 277 U.S. 438, 455 (1928) (examining whether “evidence of private telephone
conversations between the defendants and others, intercepted by means of wire tapping, amounted to a violation of the Fourth
and Fifth Amendments”). Over the past century, federal courts have considered the extent to which the Fourth Amendment’s
prohibition of unreasonable searches and seizures limits law enforcement’s use of such technologies. See, e.g., Kyllo, 533
U.S. at 2; Olmstead, 277 U.S. at 455. In 2026, the Supreme Court considered the constitutionality of searches involving a
relatively new, technology-assisted law enforcement tool—geofences. Chatrie v. United States, 146 S. Ct. 2193 (2026). The
Court ruled, for the first time, that a search occurs for purposes of the Fourth Amendment when law enforcement accesses
geofence data. Some state courts have opined on the constitutionality of similar investigatory tools, including those known as
keyword warrants. E.g., People v. Seymour, 536 P.3d 1260 (Colo. 2023).
Both geofence and keyword warrants are sometimes described as reverse warrants. Using a reverse warrant, law enforcement
essentially works backwards from the traditional process of identifying a known suspect and then obtaining a search warrant
to gather information on that suspect. Instead, with a reverse warrant, law enforcement first identifies facts that may
constitute incriminating evidence, such as the time and location of a crime or an internet search for an address where a crime
occurred. Law enforcement then attempts to identify a suspect by compelling user information correlating to those facts from
a technology provider. See, e.g., id. at 1268 (describing how and why law enforcement obtained keyword warrant); see also
United States v. Smith, 110 F.4th 817, 826 (5th Cir. 2024), cert. denied, 146 S. Ct. 356 (2025) (describing law enforcement
use of geofence warrant in particular case).
The use of reverse warrants, particularly geofence warrants, has garnered media attention and legislative interest at the state
and federal levels. In 2023, Google announced that it would reduce the default length of time it stores the location
information typically sought by geofence warrants. It also announced that it would migrate user data from Google servers to
users’ individual devices, which could effectively make it impossible for Google to share user location data with law
enforcement. The move drew interest from some observers who believe it could significantly curtail the use of geofence
warrants, although at least one federal appellate court has observed that, as of 2024, the government was still seeking
geofence data from Google. Smith, 110 F.4th at 822 n.3. Law enforcement may also continue to seek geofence data or other
information covered in this report from other companies.
This report summarizes Fourth Amendment principles and discusses the caselaw surrounding reverse warrants, including the
Supreme Court’s recent decision in Chatrie. It also examines other evolving legal issues regarding reverse warrants and
concludes with considerations for Congress.

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Reverse Warrants and the Fourth Amendment

Contents
Introduction ..................................................................................................................................... 1
Background: Technology and the Fourth Amendment .................................................................... 3
Geofence Warrants .......................................................................................................................... 6
Google’s Policies and Procedures Regarding Geofence Warrants ............................................ 8
Fourth and Fifth Circuit Decisions on the Constitutionality of Geofence Searches ................. 9
Is the Collection of Geofence Data a “Search”? ................................................................. 9
Does a Geofence Warrant Satisfy the Requirements of the Fourth Amendment? ............ 12
The Supreme Court’s Decision in Chatrie .................................................................................... 13
Keyword Warrants ......................................................................................................................... 16
Policies and Procedures........................................................................................................... 17
Constitutionality of Keyword Warrants................................................................................... 17
Congressional Considerations ....................................................................................................... 19

Tables
Table 1. Cell Tower Dumps ............................................................................................................. 5
Table 2. The Stored Communications Act ......................................................................................11
Table 3. Selected CRS Products on the Fourth Amendment, Technology, and Related
Topics ......................................................................................................................................... 21

Contacts
Author Information........................................................................................................................ 21

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Introduction
When law enforcement obtains a search warrant, they are traditionally focused on a “known
suspect.”1 After a robbery, for example, law enforcement may be able to identify a suspect based
on information gathered from witnesses or from physical evidence like fingerprints found in a
recovered getaway vehicle.2 From there, they may seek to obtain a warrant to search the dwelling
of the robbery suspect if there is probable cause that evidence of that crime (e.g., stolen currency)
will be found there.3
Sometimes, however, law enforcement may know the approximate time and location of a robbery
but not the identities of any suspects.4 These conditions may prompt law enforcement to try to
identify suspects through the execution of what has become known as a reverse warrant. With a
reverse warrant, law enforcement essentially works backwards from a “potentially incriminating
piece of evidence” and looks for user information “implicated by that evidence” to identify a
suspect.5 In other words, according to one court, in a typical search warrant, police might “seek
information on a particular suspect,” but with a reverse warrant, police might instead “seek
information that would lead to the identity of a suspect.”6 Reverse warrants are relatively new,
and two prominent emerging forms of such warrants are geofence warrants and keyword
warrants.7 In executing a geofence warrant, law enforcement compels a company to provide
certain information identifying the particular smartphones that were present within a geographic
area during a specified time frame.8 Law enforcement can then use the information to potentially
identify the owners of any smartphones found in the area of interest during the time frame.9 With

1 United States v. Smith, 110 F.4th 817, 822 (5th Cir. 2024), cert. denied, 146 S. Ct. 356 (2025) (quoting United States

v. Rhine, 652 F. Supp. 3d 38, 66 (D.D.C. 2023)) (explaining how reverse warrants differ from “traditional search
warrants”).
2 E.g., United States v. Jackson, 756 F.2d 703, 705 (9th Cir. 1985).
3 Id. (“It was a reasonable inference that [the Defendant] might keep stolen currency in his apartment from a bank
robbery two months earlier . . . . The magistrate’s substantial basis for concluding that probable cause existed is
apparent.”). More information about warrants, the Fourth Amendment, and the Federal Rules of Criminal Procedure
may be found in CRS Legal Sidebar LSB11165, Disrupting Botnets: An Overview of Seizure Warrants and Other
Legal Tools, by Peter G. Berris (2024).
4 Smith, 110 F.4th at 822; see also United States v. Chatrie, 590 F. Supp. 3d 901, 905 (E.D. Va. 2022), aff’d, 107 F.4th
319, 325 (4th Cir. 2024), aff’d en banc, 136 F.4th 100 (4th Cir. 2025) (per curiam) (describing when officers turned to
geofence warrant in underlying case), cert. granted in part, No. 25-112, 2026 WL 120676 (U.S. Jan. 16, 2026) (mem.).
5 People v. Seymour, 536 P.3d 1260, 1268 n.1 (Colo. 2023).
6 In re Search of Info. that is Stored at the Premises Controlled by Google LLC, 579 F. Supp. 3d 62, 84 n.19 (D.D.C.
2021) (mem.) (emphasis added).
7 See, e.g., Reverse Search Warrants, NAT’L ASS’N OF CRIM. DEF. LAWYERS, https://www.nacdl.org/Landing/ReverseSearch-Warrants [https://perma.cc/7VN6-HE7N] (last visited Aug. 25, 2025) (describing “reverse search warrants” as
including “geofence warrants and keyword search warrants”); cf. In re Search of Info. that is Stored at the Premises
Controlled by Google LLC, 579 F. Supp. 3d at 84 n.19 (“Some of the public criticism directed toward geofence
warrants is that they fall into the category of so-called ‘reverse warrants,’ which do not seek information on a particular
suspect, but rather seek information that would lead to the identity of a suspect, compromising third parties’ privacy
interests in the process.”).
8 Smith, 110 F.4th at 822.
9 This typically involves a three-step process that begins with anonymized information and ultimately may yield
deanonymized data as well. See infra Table 1.

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a keyword10 warrant, law enforcement obtains the account information of users who entered a
particular search term into a search engine, such as the address where a crime occurred.11
Caselaw on reverse searches was somewhat scarce prior to the Supreme Court’s decision in
Chatrie.12 Much of the limited jurisprudence on the issue focused specifically on geofence
warrants,13 likely because such warrants have, in some recent years, numbered in the thousands.14
In assessing the Fourth Amendment implications of geofence warrants, courts have considered
two primary constitutional issues. The first is whether the collection and subsequent review of
data pursuant to a reverse warrant is in itself a “search” implicating the protections of the Fourth
Amendment. If it is a search, the second question is whether a properly issued warrant is
sufficient protection under the Fourth Amendment to permit the use of the seized data as
evidence.15 In Chatrie, the Supreme Court resolved the first of those questions, finding in the
affirmative.16
Legal challenges to the constitutionality of reverse warrants remain, however,17 including in
Chatrie.18 The Supreme Court remanded the case to the U.S. Court of Appeals for the Fourth
Circuit (Fourth Circuit) for consideration of the second question, regarding whether a properly
issued warrant is sufficient protection under the Fourth Amendment, in light of its holding that a
search occurs in the collection and subsequent review of geofence data.19
Given congressional interest in the intersection of law enforcement and technology,20 this report
examines select legal issues that may arise in investigations and prosecutions involving reverse
warrants, with a focus on geofence and keyword searches. The report first provides background
on jurisprudence involving the Fourth Amendment and technology before turning to analyze the
procedures typically employed by a company in response to law enforcement demands for
10 Given the relatively new emergence of these warrants, the terminology used to discuss them is sometimes

inconsistent. For simplicity’s sake, this report uses “keyword warrants” to describe those executed in accordance with
the procedures described infra, “Keyword Warrants.” “Keyword warrants,” as used in this report, does not refer to
warrants for a known individual’s search history.
11 People v. Seymour, 536 P.3d 1260, 1268 n.1 (Colo. 2023). As with geofence warrants, this typically involves a
multistep process, discussed below. See infra “Policies and Procedures.”
12 See Smith, 110 F.4th at 821 (“As a relic of their novelty, ‘[t]here is a relative dearth of case law addressing geofence
warrants.’” (quoting United States v. Chatrie, 590 F. Supp. 3d 901, 906 (E.D. Va. 2022))); Seymour, 536 P.3d at 1269
(“The constitutionality of reverse-keyword warrants presents an issue of first impression in Colorado. Indeed, to our
knowledge, no state supreme court or federal appellate court has addressed the constitutionality of such warrants.”).
13 But see, e.g., Seymour, 536 P.3d at 1267–68 (examining keyword warrants).
14 See infra Table 1. As discussed below, a policy change at the company that receives the most geofence warrants
(Google) may affect their prevalence moving forward. See discussion infra notes 93–98.
15 Chatrie v. United States, 146 S. Ct. 2193, 2199 (2026).
16 Id. at 2199-2200.
17 See, e.g., Chatrie, 590 F. Supp. 3d at 905, aff’d, 107 F.4th 319, 325 (4th Cir. 2024), aff’d en banc, 136 F.4th 100 (4th
Cir. 2025) (per curiam), cert. granted in part, No. 25-112, 2026 WL 120676 (U.S. Jan. 16, 2026).
18 Chatrie, 136 F.4th 100 (4th Cir. 2025) (per curiam), vacated, 146 S. Ct. 2193 (2026).
19 146 S. Ct. at 2199-2200.
20 E.g., Letter from Rep. Jim Jordan, Chairman, H. Judiciary Comm., to Merrick Garland, Att’y Gen., U.S. Dep’t of
Just. (Aug. 10, 2023), https://judiciary.house.gov/sites/evo-subsites/republicans-judiciary.house.gov/files/evo-mediadocument/2023-08-10-jdj-to-doj-re-geofencing.pdf [https://perma.cc/D2N4-HWZN] (describing oversight efforts on
“how federal law enforcement uses geofence warrants”); Press Release, Alex Padilla, Senator, U.S. Senate, Padilla
Calls on Google to Limit Collection and Storage of Location Data as Republicans Seek to Criminalize Abortion (May
25, 2022), https://www.padilla.senate.gov/newsroom/press-releases/padilla-calls-on-google-to-limit-collection-andstorage-of-location-data-as-republicans-seek-to-criminalizeabortion%EF%BF%BC/#:~:text=WASHINGTON%2C%20D.C.,obtain%20reproductive%20health%20care
[https://perma.cc/N6EL-U25H].

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geofence or keyword data. The report then discusses the Supreme Court’s decision in Chatrie,
other relevant caselaw relating to reverse warrants, and the constitutional issues present. The
report concludes with considerations for Congress.

Background: Technology and the Fourth
Amendment
The Fourth Amendment limits searches and seizures by the government.21 Some law enforcement
efforts to obtain information constitute a search or a seizure within the meaning of the Fourth
Amendment as it is interpreted by courts, but others may not.22 In determining whether a
particular means of gathering information—such as the use of a geofence—constitutes a “search”
triggering Fourth Amendment protections, federal courts generally look to whether the
government action involves physical intrusion into a constitutionally protected area23 or violates a
person’s “subjective expectation of privacy that society recognizes as reasonable.”24
A variety of considerations informs whether an expectation of privacy is reasonable, but the
Supreme Court has held that “a person has no legitimate expectation of privacy in information he
voluntarily turns over to third parties.”25 This concept—known as the “third-party doctrine”26—
reflects a judgment that a person “takes the risk, in revealing his affairs to another, that the
information will be conveyed by that person to the Government.”27 In articulating this doctrine,
the Supreme Court in 1976 concluded that a bank customer lacked a reasonable expectation of
privacy in financial records stored with his bank by virtue of his being a customer there.28 Three
years later, the Court concluded that there was no reasonable expectation of privacy in numbers
dialed on a landline telephone because “telephone users realize that they must ‘convey’ phone
numbers to the telephone company” and in so doing they “assume[] the risk” that the information
may be revealed to the police.29

21 U.S. CONST. amend. IV (“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.”). For a discussion of the “state action doctrine,” which applies Fourth Amendment protections to the actions of
private parties when they act as an instrument or agent of the government, see CRS Legal Sidebar LSB10713, The
Fourth Amendment and the Internet: Legal Limits on Digital Searches for Child Sexual Abuse Material (CSAM), by
Michael A. Foster (2022). Other discussions of Fourth Amendment jurisprudence in various contexts may be found in
additional CRS products. See infra Table 3.
22 Compare Katz v. United States, 389 U.S. 347, 348, 353 (1967) (holding FBI agents’ use of an electronic listening
and recording device to surveil a public telephone booth constituted a search), with Oliver v. United States, 466 U.S.
170, 179 (1984) (reasoning open fields “do not provide the setting for those intimate activities that the [Fourth]
Amendment is intended to shelter from government interference or surveillance”).
23 United States v. Jones, 565 U.S. 400, 407 n.3 (2012) (“Where . . . the Government obtains information by physically
intruding on a constitutionally protected area . . . a search has undoubtedly occurred.”).
24 Kyllo v. United States, 533 U.S. 27, 33 (2001); see also Smith v. Maryland, 442 U.S. 735, 740 (1979) (similar);
Cong. Rsch. Serv., Katz and Reasonable Expectation of Privacy Test, CONSTITUTION ANNOTATED,
https://constitution.congress.gov/browse/essay/amdt4-3-3/ALDE_00013717/ (last visited Feb. 24, 2025) (providing
overview of caselaw concerning expectations of privacy).
25 Smith, 442 U.S. at 743–44; accord Carpenter v. United States, 585 U.S. 296, 304 (2018).
26 United States v. Trader, 981 F.3d 961, 967 (11th Cir. 2020).
27
United States v. Miller, 425 U.S. 435, 443 (1976).
28 Id.
29 Smith, 442 U.S. at 742, 744.

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Given the ubiquity of computers and smartphones, and the omnipresence of the internet in the
modern era,30 a strict application of the third-party doctrine may have different implications today
than it did in the 1970s. Under a broad construction of the doctrine, a potentially vast amount of
digital information would fall outside the protections of the Fourth Amendment, because such
information is often shared by customers with technology providers in the ordinary course of
using a product.31
The use of new technological investigative techniques by law enforcement has resulted in a series
of Supreme Court opinions reexamining the contours of the Fourth Amendment with respect to
emerging technologies and, in one case, limiting the scope of the third-party doctrine. Aside from
the newly issued opinion in Chatrie,32 the Supreme Court in 2012 decided United States v. Jones,
in which it evaluated the application of the Fourth Amendment to Global Positioning System
(GPS) tracking devices.33 In Jones, law enforcement affixed a GPS device to a suspect’s car
without a warrant and monitored the vehicle’s movements for 28 days.34 The Court held that by
attaching the GPS device to the vehicle, law enforcement “physically occupied private property
for the purpose of obtaining information,”35 which amounted to a Fourth Amendment search.
Across two separate concurrences, five Justices agreed that “longer term GPS monitoring in
investigations of most offenses impinges on expectations of privacy.”36
Two years after Jones, the Supreme Court issued its opinion in Riley v. California, recognizing
the unique privacy implications resulting from digital searches of cell phones.37 The Riley Court
distinguished cell phones from other objects that a person might carry in light of the
pervasiveness of the technology, the “immense storage capacity” of “modern cell phones,” the
large variety of types of information that phones contain, and the prolonged period of time that
information may cover.38 With a cell phone, the Court wrote, the “sum of an individual’s private
life can be reconstructed through a thousand photographs labeled with dates, locations, and
descriptions; the same cannot be said of a photograph or two of loved ones tucked into a
wallet.”39
In 2018, the Supreme Court decided Carpenter v. United States,40 which involved the warrantless
search of historical cell-site location information (CSLI)—data that record the location of a
cellular device when it connects to “a set of radio antennas called ‘cell sites’” typically mounted

30 See Press Release, U.S. Census Bureau, Computer and Internet Use in the United States: 2021 (June 18, 2024),

https://www.census.gov/newsroom/press-releases/2024/computer-internet-use-2021.html [https://perma.cc/E69BJ3DC] (“Most U.S. households had at least one type of computer (95%) and had a broadband internet subscription
(90%) in 2021, an increase from 2018 (92% and 85%, respectively).”). According to the Census Bureau, “Smartphones
were the most common computing device in U.S. households (90%), followed by desktop or laptop computers (81%)
and tablets (64%) in 2021.” Id.
31 See S. REP. NO. 99-541, at 3 (1986) (discussing the proliferation of computers and the result that categories of
electronic “information may be subject to no constitutional privacy protection” because they are “subject to control by
a third party computer operator”).
32 See infra “The Supreme Court’s Decision in Chatrie.”
33 565 U.S. 400 (2012).
34 Id. at 403.
35 Id. at 404.
36 Id. at 415 (Sotomayor, J., concurring); id. at 420 (Alito, J., concurring).
37 573 U.S. 373 (2014).
38
Id. at 393–95.
39 Id. at 394.
40 585 U.S. 296 (2018).

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on towers or structures.41 In Carpenter, law enforcement obtained a defendant’s CSLI covering
127 days from cellular providers through a court order issued pursuant to the Stored
Communications Act (SCA; discussed in Table 2 below).42 The Carpenter Court held that the
CSLI was not exempt from Fourth Amendment protection pursuant to the third-party doctrine,
even though the CSLI was shared by the defendant with cellular providers in the course of his cell
phone use.43 The Court rejected the idea that the defendant’s sharing of CSLI with the providers
was voluntary. Echoing the Court’s concerns in Riley, the Carpenter Court observed that “[c]ell
phone location information is not truly ‘shared’ as one normally understands the term” given that
carrying a cell phone is “indispensable to participation in modern society” and “a cell phone logs
a cell-site record by dint of its operation.”44 In addition, the Court concluded that the defendant
had a reasonable expectation of privacy in the CSLI in light of the revealing nature of the
information at issue, which the Court observed amounted to “near perfect surveillance” because
cell phones accompany their owners in nearly every physical space and because the CSLI is both
precise and retrospective.45 As the Court in Carpenter put it, CSLI can provide “an intimate
window into a person’s life, revealing not only his particular movements, but through them, his
‘familial, political, professional, religious, and sexual associations.’”46 Nevertheless, the Court
described its holding as a “narrow” one that did not abolish the third-party doctrine or
predetermine its application to other technological surveillance.47 At least some federal courts
have been reluctant to extend Carpenter to other digital contexts.48
Table 1. Cell Tower Dumps
Some federal courts have examined whether the Carpenter exception to the third-party doctrine extends to cell
tower dumps, or “a download of information on all the devices that connected to a particular cell-site during a
particular interval.”49 As one court explained, “In a tower dump . . . law enforcement identifies the cell towers
near the scene of a crime and seeks ‘a list of the telephone numbers that connected to the cell towers during the
pertinent time period,’ along with date, times, and telephone numbers for connecting calls.”50 In other words,
while historical CSLI is “narrowly targeted” towards a particular person but “quite expansive as to that person,”
tower dumps “are narrow as to the individual suspect—they typically seek location data, cell numbers, and
subscriber information—but are broad as to third-party data, collecting all phone numbers for users who
connected to the relevant cell towers.”51
The Carpenter Court expressly declined to weigh in on the constitutionality of tower dumps,52 and federal courts
have split on the issue.53 A federal district court in Michigan concluded that there is no reasonable expectation of
privacy in five hours’ worth of short-term CSLI disclosed via a tower dump, since it “was magnitudes short of the

41 Id. at 300.
42 Id. at 301–02; infra Table 2.
43 Id. at 309–10.
44 Id. at 315.
45 Id. at 311–12.
46 Id. at 311 (quoting United States v. Jones, 565 U.S. 400, 415 (2012) (Sotomayor, J., concurring)).
47 Id. at 316.
48 See infra “Is the Collection of Geofence Data a “Search”?”
49 Carpenter, 585 U.S. at 316.
50 United States v. Medina, 712 F. Supp. 3d 226, 237 (D.R.I. 2024), vacated and remanded on other grounds, 125 F.4th

310 (1st Cir. 2025) (quoting In re Application of the U.S.A. for an Ord. Pursuant to 18 U.S.C. 2703(c), 2703(d)
Directing AT&T, Sprint/Nextel, T-Mobile, Metro PCS, Verizon Wireless, 42 F. Supp. 3d 511 (S.D.N.Y. 2014)).
51
Id. at 238.
52 Carpenter, 585 U.S. at 316.
53 See, e.g., United States v. Pricop, 775 F. Supp. 3d 1036, 1038–39 (D. Ariz. 2025) (collecting cases).

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seven days of close location tracking in Carpenter.”54 In other words, that court rejected the idea that the tower
dump provided the comprehensive chronicle of past movements that troubled the Carpenter Court.55 At least one
federal court reached a different conclusion, holding that there is a reasonable expectation of privacy in shortterm CSLI revealed through a tower dump, triggering the warrant requirement under the Fourth Amendment
(although that court ultimately affirmed the collection of tower dump data in question under the good faith
exception, discussed below).56 The court concluded that tower dumps provide “‘near perfect surveillance’ of a
population at a moment in time,” reveal intimate information, and provide a cheap and efficient investigative
technique that “would be impossible to do with traditional surveillance.”57 Like in Carpenter, the Court in Chatrie v.
United States did not specifically address tower dumps.

Geofence Warrants
Geofences have been described as electronic systems that establish a virtual perimeter around a
specific geographic location.58 Private companies use geofences for business purposes such as
targeted advertising.59 Geofence warrants are an investigative tool employed by law enforcement
to gather location information revealing which smartphones were at or near the scene of a crime
when it was committed.60 Law enforcement has used geofence warrants to investigate criminal
matters ranging from homicides61 to “stolen pickup trucks and smashed car windows.”62 The
scope of geofence warrants has varied as well. Some geofence warrants have covered
geographical areas measured in feet or meters;63 others have encompassed areas larger than an
acre.64 Temporally, some have been limited to minutes or hours;65 others have covered a period of
days.66 For example, in one case law enforcement used a geofence warrant to obtain information
from Google that ultimately revealed the identities of individuals who were present at the scene

54 United States v. Williams, 741 F. Supp. 3d 642, 650 (E.D. Mich. 2024).
55 Id.
56 Medina, 712 F. Supp. 3d at 246, 248; infra notes 100–102 and accompanying text.
57 Id. at 242–43 (quoting Carpenter, 585 U.S. at 309–13). A number of state courts have considered cell tower dumps.

See, e.g., Commonwealth v. Kurtz, 294 A.3d 509, 530 (Pa. Super. Ct. 2023) (holding that defendant had no legitimate
expectation of privacy concerning tower dump data produced to law enforcement by AT&T), aff’d on other grounds,
Nos. 98 MAP 2023, 99 MAP 2023, 100 MAP 2023, 2025 WL 3670767 (Pa. Dec. 16, 2025); State v. Bryant, No. A1399-24, 2025 WL 3481348, at *7 (N.J. Super. Ct. App. Div. Dec. 4, 2025) (holding that “tower dump searches can be
constitutional, but they need a warrant, and the warrant must be particularized and supported by probable cause”);
Commonwealth v. Perry, 184 N.E.3d 745, 752 (Mass. 2022) (examining legality of tower dumps under Massachusetts
law).
58 Brian L. Owsley, The Best Offense is a Good Defense: Fourth Amendment Implications of Geofence Warrants, 50
HOFSTRA L. REV. 829, 832 (2022).
59 Id.
60 Chatrie, 590 F. Supp. 3d at 905, aff’d, 107 F.4th 319, 325 (4th Cir. 2024), aff’d en banc, 136 F.4th 100 (4th Cir.
2025) (per curiam), cert. granted in part, No. 25-112, 2026 WL 120676 (U.S. Jan. 16, 2026). In this sense, geofence
warrants share some conceptual similarities with cell tower dumps, discussed above. See supra Table 1.
61 State v. Contreras-Sanchez, 5 N.W.3d 151, 156 (Minn. Ct. App. 2024).
62 United States v. Smith, 110 F.4th 817, 822 (5th Cir. 2024), cert. denied, 146 S. Ct. 356 (2025).
63 Contreras-Sanchez, 5 N.W.3d at 156; Chatrie, 107 F.4th at 324.
64 In re Search of Info. that is Stored at Premises Controlled by Google, No. 2:22-MJ-01325, 2023 WL 2236493, at *10
(S.D. Tex. Feb. 14, 2023).
65 Chatrie, 107 F.4th at 324; In re Search of Info. that is Stored at the Premises Controlled by Google LLC, 579 F.
Supp. 3d. 62, 72 (D.D.C. 2021).
66 Contreras-Sanchez, 5 N.W.3d at 158.

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of a robbery of a postal service employee.67 The warrant sought Location History68 data
corresponding to a one-hour period during which the robbery occurred and “a geofence covering
approximately 98,192 square meters” surrounding the scene of the crime.69 The acquired
information enabled law enforcement not only to identify the individuals present at the scene, but
also to ascertain the precise time that the individuals were there and, accordingly, establish
evidence of their involvement in the crime.70
Google has reportedly been the primary recipient of geofence warrants.71 In 2019, Google
received roughly 9,000 geofence requests from law enforcement, and by 2021, more than 25% of
all warrants that Google received in the United States were for geofence data.72 For comparison,
Apple reported receiving 36 geofence warrants from law enforcement in 202273 and 26 in 2023.74
Google’s centrality in the phenomenon of geofence warrants is “in large part due to its extensive
Location History database known as the ‘Sensorvault.’”75 According to Google, Location History
is “a history or journal that [its] users can choose to create, edit, and store to record their
movements and travels.”76 Google users are not automatically subject to the collection of their
Location History: Google users must agree to have their Location History monitored.77 As of
October 2018, Google estimated that approximately one-third of its users, equating to 592 million
individuals, had opted in to share their Location History.78 Location History allows Google to
“‘potentially locate an individual within about sixty feet or less,’ and in certain circumstances,
down to three meters.”79 Location History may even be able to ascertain a particular device’s
elevation, including what floor of a building it is on.80 Location History does not, however,
determine an individual’s location with “absolute precision.”81 Rather, specific datapoints in a
device’s Location History are reported with a “confidence interval,”82 which reflects Google’s
confidence in the accuracy of the estimated locations. As summarized by the United States Court
67 Smith, 110 F.4th at 826.
68 For clarity, this report capitalizes the term “Location History” when referring to Google Location History

information, described below. See infra notes 75–84, 93–98 and accompanying text.
69 Id. at 827.
70 Id. at 820.
71 Id. at 822.
72 Id. at 821–22.
73 APPLE INC., APPLE TRANSPARENCY REPORT: GOVERNMENT AND PRIVATE PARTY REQUESTS, JANUARY 1-JUNE 30, 2022
tbl. 11 (2022), https://www.apple.com/legal/transparency/pdf/requests-2022-H1-en.pdf#page=14
[https://perma.cc/7PRN-JPLP]; APPLE INC., APPLE TRANSPARENCY REPORT: GOVERNMENT AND PRIVATE PARTY
REQUESTS, JULY 1-DECEMBER 31, 2022 tbl. 14 (2022), https://www.apple.com/legal/transparency/pdf/requests-2022H2-en.pdf#page=16 [https://perma.cc/T378-Z3BX].
74 APPLE INC., APPLE TRANSPARENCY REPORT: GOVERNMENT AND PRIVATE PARTY REQUESTS, JANUARY 1-JUNE 30, 2023
tbl. 14 (2023), https://www.apple.com/legal/transparency/pdf/requests-2023-H1-en.pdf#page=17
[https://perma.cc/5ZVB-VQVC]; APPLE INC., APPLE TRANSPARENCY REPORT: GOVERNMENT AND PRIVATE PARTY
REQUESTS, JULY 1-DECEMBER 31, 2023 tbl. 14 (2023), https://www.apple.com/legal/transparency/pdf/requests-2023H2-en.pdf#page=17 [https://perma.cc/WCQ8-4AZS].
75 Smith, 110 F.4th at 822.
76 Brief of Amicus Curiae Google LLC in Support of Neither Party Concerning Defendant’s Motion to Suppress
Evidence from “Geofence” General Warrant at 6, United States v. Chatrie, 590 F. Supp. 3d 901 (E.D. Va. 2022) (No.
3:19-CR-00130), Dkt. No. 59-1.
77 Id. at 835.
78 Id. at 823.
79 Id. at 823 (quoting Owsley, supra note 58, at 835).
80
Id. at 824.
81 Id.
82 Id.

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of Appeals for the Fifth Circuit,83 “[t]he smaller the radius, the more confident Google is in th[e]
phone’s exact location.”84

Google’s Policies and Procedures Regarding Geofence Warrants
In practice, the unsettled legal terrain surrounding geofence warrants (discussed more below) has
meant that the procedures for executing them have been driven in large part by the corporate
policies of Google.85 Under Google’s three-step process for geofence requests, law enforcement
must first obtain a judicial warrant “compelling Google to disclose an anonymized list of all
Google user accounts” with saved Location History information corresponding to a specified
geographic area and time frame.86 Second, after the government reviews the information provided
by Google at step one, it “can compel Google to provide additional contextual location
coordinates beyond the time and geographic scope of the original request.”87 Given the loosened
“geographical and temporal limits” on the scope of information at step two, “Google generally
requires law enforcement to narrow its request for this more expansive location data to only a
subset of the users pinpointed in Step One.”88 Third, “the government can compel Google to
provide account-identifying information,” such as account holder names and email addresses,
associated with the anonymized device numbers that law enforcement has identified as relevant
under step two.89 What it actually means to “compel” Google beyond step one seems to vary in
practice. In one case, the United States Postal Inspection Service relied on the initial search
warrant to compel Google at all three steps.90 By contrast, a county detective in Minnesota
obtained an additional warrant to compel deanonymized data from Google at step three.91 Google
has described the three-step process as “typically” followed, while some contend that it is often
subject to case-specific negotiations between law enforcement and Google.92
Google’s policies with respect to data collection and storage also have an impact on the amount of
data that is available for law enforcement to obtain in the first place. In 2023, Google announced
that it reduced the default length of its storage of Location History from 18 months to three
83 This report references decisions by federal appellate courts of various regional circuits. For purposes of brevity,

references to a particular circuit in this report (e.g., the Fifth Circuit) refer to the U.S. Court of Appeals for that
particular circuit (e.g., the U.S. Court of Appeals for the Fifth Circuit).
84 Smith, 110 F.4th at 824.
85 Id.
86 Brief of Amicus Curiae Google LLC in Support of Neither Party Concerning Defendant’s Motion to Suppress
Evidence from “Geofence” General Warrant at 12, United States v. Chatrie, 590 F. Supp. 3d 901 (E.D. Va. 2022) (No.
3:19-CR-00130), Dkt. No. 59-1.
87 Id. at 13.
88 United States v. Chatrie, 107 F.4th 319, 324 (4th Cir. 2024), aff’d en banc, 136 F.4th 100 (4th Cir. 2025) (per
curiam), cert. granted in part, No. 25-112, 2026 WL 120676 (U.S. Jan. 16, 2026).
89 Brief of Amicus Curiae Google LLC in Support of Neither Party Concerning Defendant’s Motion to Suppress
Evidence from “Geofence” General Warrant at 14, United States v. Chatrie, 590 F. Supp. 3d 901 (E.D. Va. 2022) (No.
3:19-CR-00130), Dkt. No. 59-1.
90 United States v. Smith, 110 F.4th 817, 828 (5th Cir. 2024), cert. denied, 146 S. Ct. 356 (2025).
91 State v. Contreras-Sanchez, 5 N.W.3d 151, 159 (Minn. Ct. App. 2024).
92 See Brief of Amicus Curiae Google LLC in Support of Neither Party Concerning Defendant’s Motion to Suppress
Evidence from “Geofence” General Warrant at 14, United States v. Chatrie, 590 F. Supp. 3d 901 (E.D. Va. 2022) (No.
3:19-CR-00130), Dkt. No. 59-1; see also Brief for Technology Law and Policy Clinic at New York University School
of Law & Electronic Frontier Foundation as Amici Curiae in Support of Defendant-Appellant at 15–16, United States
v. Chatrie, 107 F.4th 319 (4th Cir. 2024) (No. 22-4489), 2023 WL 1368629 (contending that “[t]he variability of
Google’s compliance practices further attests to the three-step procedure’s unreliability as a guardrail against police
discretion. Even Google presents the three-step procedure as a policy that is ‘typically’ followed, not stringently
observed.”).

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months.93 Google also said that it would store Location History on user devices rather than in the
Sensorvault.94 Some observers believe these changes could significantly curtail the use of
geofence warrants.95 Still, litigation on geofence warrants that predate the policy change remains
pending, and at least one federal appellate court has observed that geofence warrants remain
logistically viable even if their scope and frequency might be diminished.96 For example, law
enforcement might seek a geofence warrant from a company other than Google.97 In addition,
caselaw on geofence warrants may inform subsequent litigation over other forms of reverse
searches such as keyword warrants, as discussed below.98

Fourth and Fifth Circuit Decisions on the Constitutionality of
Geofence Searches
As previously discussed, determining the constitutionality of geofence searches has typically
involved two discrete analyses—whether the collection of geofence data itself constitutes a
Fourth Amendment search, and if so, whether a judicial warrant provides satisfactory protection
under the Fourth Amendment. In 2024, courts in the Fourth and Fifth Circuits issued diverging
opinions on whether the collection of geofence data by law enforcement amounts to a Fourth
Amendment search. This section addresses those decisions.

Is the Collection of Geofence Data a “Search”?
In United States v. Chatrie, the district court denied the defendant’s motion to suppress geofence
evidence.99 Although the district court concluded that the underlying geofence warrant “plainly”
violated the Fourth Amendment, it declined to exclude the evidence pursuant to the “good faith”
exception to the Fourth Amendment.100 That exception does not require the exclusion of evidence
garnered by “officers acting in reasonable reliance on a search warrant issued by a detached and
93 Marlo McGriff, Updates to Location History and new controls coming soon to Maps, GOOGLE (Dec. 12, 2023),

https://blog.google/products/maps/updates-to-location-history-and-new-controls-coming-soon-to-maps/
[https://perma.cc/9Y4K-ACJL].
94 Id.; Google said that it would allow users to back up that data in the cloud, where it would be “automatically
encrypt[ed] . . . so no one can read it, including Google.” See also Lars Daniel, Google to Stop Giving Location
Evidence to Law Enforcement, FORBES, June 14, 2025 (describing Google policy shift).
95 See, e.g., Chatrie v. United States, 146 S. Ct. 2193, 2225 (2026) (Alito, J., dissenting) (“The answer to [whether the
geofence procedure that the police used here comports with the Fourth Amendment] has scarcely any ongoing
significance,” owing to Google’s change in policy.); Smith, 110 F.4th at 822 n.3.
96 Id.; compare Petition for Writ of Certiorari at 10, Chatrie v. United States, No. 25-112 (U.S. July 28, 2025) (“Though
Google announced that it intended to make this change gradually over the year between 2023 and 2024, petitioner is
not aware of any subsequent announcements that the change has been made, detailing how the change affects legacy
Google devices, or specifying which data Google continues to collect. Geofence warrants continue to be litigated.”),
with Brief for the United States in Opposition at 18, Chatrie v. United States, No. 25-211 (U.S. Nov. 24, 2025). (“This
Office has been informed that all Location History data was deleted from Google’s Sensorvault database by the end of
July 2025. Accordingly, it is the government’s understanding that Google will be unable to respond to geofence
warrants going forward, except to the extent that Google retains data responsive to specific geofence warrants or
geofence preservation requests received before that date.”).
97 See discussion infra notes 73–74; see also Smith, 110 F.4th at 822 n.2 (stating that “Companies such as Apple, Lyft,
Snapchat, and Uber have all received geofence warrant requests.”) (citing Note, Geofence Warrants and the Fourth
Amendment, 134 HARV. L. REV. 2508, 2512–13 (2021)).
98 See infra “Keyword Warrants.”
99 United States v. Chatrie, 590 F. Supp. 3d 901, 905, 918–19 (E.D. Va. 2022), aff’d, 107 F.4th 319, 325 (4th Cir.
2024), aff’d en banc, 136 F.4th 100 (4th Cir. 2025) (per curiam), cert. granted in part, No. 25-112, 2026 WL 120676
(U.S. Jan. 16, 2026).
100 Id. at 905, 925 (quoting United States v. Leon, 468 U.S. 897 (1984)).

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neutral magistrate but ultimately found to be unsupported by probable cause.”101 The underlying
rationale is that excluding evidence in such a scenario would not have a “deterrent effect when
the offending officers acted in the objectively reasonable belief that their conduct did not violate
the Fourth Amendment.”102
On appeal, a Fourth Circuit panel, declining to extend Carpenter to a search of Google’s Location
History information, concluded that the defendant lacked a reasonable expectation of privacy in
that information.103 First, the court determined that because the geofence warrant at issue sought
only two hours of Location History, the privacy implications were far more limited than they
were with the CSLI at issue in Carpenter or the GPS monitoring in Jones.104 Second, the Fourth
Circuit panel said that Location History, unlike CSLI, is voluntarily shared because it “is off by
default and can be enabled only by a user’s affirmative act.”105 Thus, the Fourth Circuit panel
held that the third-party doctrine applied.106
However, in November of 2024, the Fourth Circuit ordered rehearing of Chatrie en banc and
subsequently heard arguments on January 30, 2025.107 The court vacated the first Chatrie panel’s
judgment and opinion on appeal,108 and on April 30, 2025, the en banc court issued a one-line per
curiam opinion, affirming the judgment of the district court.109
The en banc Fourth Circuit “fractured”110 in its reasoning, in what the Chief Judge described as a
“labyrinth” of eight separate concurrences and one dissent, representing “widely divergent views
on the intersection of the Fourth Amendment and the groundbreaking investigative tool at issue
here.”111 Fourteen of the Circuit’s fifteen judges joined the per curium opinion.112 A majority of
the en banc court (across several opinions) agreed that the officers benefited from the good faith
exception.113 Nearly half of the en banc court would have concluded that the collection of
101

Leon, 468 U.S. at 900.

102 Id. at 918.
103 Chatrie, 107 F.4th at 324.
104 Id. at 330.
105 Id. at 332.
106 Id.
107 United States v. Chatrie, 136 F.4th 100 (4th Cir. 2025) (per curiam), cert. granted in part, No. 25-112, 2026 WL

120676 (U.S. Jan. 16, 2026). For additional discussion of the significance of en banc rehearings, see CRS Report
R48369, The United States Courts of Appeals: Background and Circuit Splits from 2024, coordinated by Michael John
Garcia (2025).
108 See 4TH CIR. R. 40(e) (“Granting of rehearing or rehearing en banc vacates the previous panel judgment and opinion
. . . .”); 4TH CIR. INTERNAL OPERATING P. 40.2.
109 Chatrie, 136 F.4th at 100.
110 Id. at 157 (Gregory, J., dissenting).
111 Id. at 101, 108–09 (Diaz, C.J., concurring).
112 Id. at 100 (collating alignment in front matter).
113 Id. at 101 (Diaz, C.J., concurring) (“I join in affirming the district court’s denial of Okello Chatrie’s suppression
motion, but solely on the court’s finding of good faith.”); id. at 114 (Niemeyer J., concurring) (“I also concur in the
judgment of the court holding that, in any event, law enforcement’s collection of the data from Google was protected
because law enforcement relied in good faith on a warrant issued by a detached and neutral judicial officer.”); id. at 115
(King, J., concurring) (“I agree that the officers acted in good faith, and I therefore also support the affirmance of the
district court’s judgment on that basis.”); id. at 115 n.1 (Wynn, J., concurring) (“Although I believe that this case
involved a Fourth Amendment search—and that we should say so—I acknowledge that the conditions for application
of the good-faith exception to the exclusionary rule are met here.”); id. at 143 (Heytens, J., concurring) (“And because
the investigating officer could have had ‘an objectively reasonable good-faith belief that [his] conduct [was] lawful,’ I
think the district court was right to withhold ‘the harsh sanction of exclusion.’”). Between these opinions, nine judges
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geofence data was not a Fourth Amendment search under various theories, including application
of the third-party doctrine.114 By contrast, several other members of the en banc court analogized
geofence information to the CSLI protected by Carpenter and would have held that it is subject to
a reasonable expectation of privacy (at least with respect to non-anonymous data).115 Some judges
also believed that the geofence warrant itself was invalid due to a lack of probable cause.116 One
judge dissented on the ground that “the good faith exception is inapplicable in this case,” and
wrote that “the geofence warrant at issue glaringly infringed on the Fourth Amendment.”117
In United States v. Smith,118 the Fifth Circuit disagreed with the original Fourth Circuit panel’s
holding in Chatrie, despite ultimately affirming the district court’s decision not to suppress
evidence on the basis of the good faith exception. Although the Fifth Circuit acknowledged that
“geofences tend to be limited temporally,” it observed that “the potential intrusiveness of even a
snapshot of precise location data should not be understated” given that “location tracking can
easily follow an individual into areas normally considered some of the most private and intimate,
particularly residences.”119 The Fifth Circuit found that, although Google Location History
information requires a user to affirmatively opt in, it is still not truly voluntary due to the opacity
of the opt-in process and the persistence with which “users are bombarded multiple times with
requests to opt in across multiple apps.”120 The Smith court further analogized geofence data to
the CSLI at issue in Carpenter and warned of “near perfect surveillance” given the pervasiveness
of the underlying technology and the precision of the information.121 However, as mentioned,
Smith ultimately affirmed the district court’s determination that suppression of the evidence in
question was not warranted due to the good faith exception.122
Table 2. The Stored Communications Act
The Fourth Amendment is not the only potential legal limit on law enforcement’s ability to obtain digital
information from providers. In the 1980s, decades before Carpenter, Congress enacted the Stored
Communications Act (SCA) as part of the Electronic Communications Privacy Act (ECPA).123 Some legislative

agreed that the good faith exception applied including: Chief Judge Diaz, and Judges Niemeyer, King, Wynn, Thacker,
Harris, Benjamin, Berner, and Heytens. Judge Gregory also joined Judge Wynn’s concurrence, but not on the statement
regarding good faith. Id. at 115.
114 Id. at 109 (Wilkinson, J., concurring) (“With due regard for my fine colleagues, there was no search here.”); id. at
113 (Niemeyer, J., concurring) (“Collecting markers such as these from public places or third persons is the stuff of law
enforcement, enabling it to solve crimes and prosecute suspects, and the person who left them behind is not ‘searched’
in his person and effects, in violation of the Fourth Amendment.”); id. at 141 (Richardson, J., concurring) (“The thirdparty doctrine therefore squarely governs this case.”)
115 Id. at 120–21 (Wynn, J., concurring) (“An application of the Carpenter factors in this case compels the conclusion
that [the defendant] had a reasonable expectation of privacy in his Location History data.”); id. at 144 (Berner, J.,
concurring) (distinguishing anonymized Location History data from non-anonymous Location History data and stating
that “individuals do have a reasonable expectation of privacy in their non-anonymous Location History data”).
116 Id. at 144 (Berner, J., concurring) (“Because the Government lacked probable cause to search any specific Google
user at the time it applied for the geofence warrant, this warrant was invalid and the Government’s search of Chatrie
violated the Fourth Amendment.”).
117 Id. at 157 (Gregory, J., dissenting).
118 110 F.4th 817 (5th Cir. 2024), cert. denied, 146 S. Ct. 356 (2025).
119 Id. at 833.
120 Id. at 835.
121 Id. at 833.
122 Id. at 840.
123 CRS Legal Sidebar LSB10801, Overview of Governmental Action Under the Stored Communications Act (SCA), by
Jimmy Balser (2022).

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history suggests that Congress’s intent in doing so was to add supplemental protections from providers’ disclosure
of stored wire and electronic communications beyond those potentially contained in the Fourth Amendment. For
instance, the Senate Judiciary report accompanying the ECPA described the proliferation of electronic data storage
and the risk that such data “may be subject to no constitutional privacy protection” because it “is subject to
control by a third party computer operator.”124 In general terms, the SCA restricts when certain information may
be disclosed by Electronic Communication Services or Remote Computing Services, which in practice typically
include entities such as “cell phone providers, email providers, or social media platforms” and cloud computing
providers.125 Pursuant to a provision of the SCA codified at 18 U.S.C. § 2703, the government may compel such
providers to share communications’ content and metadata if it obtains the requisite level of legal process, which
ranges from a subpoena to a warrant, depending on the category of information sought.126 Google has argued that,
“quite apart” from the constitutional warrant requirement, § 2703(a) and (b) separately require law enforcement
to obtain a warrant to compel the disclosure of Location History information.127 It appears that some geofence
warrant applications expressly invoke § 2703, and some courts have cited the statute as authorizing particular
geofence warrants.128 The limited geofence caselaw that exists, however, has primarily been resolved on Fourth
Amendment grounds. Analysis of the SCA and related considerations may be found in CRS Legal Sidebar
LSB10801, Overview of Governmental Action Under the Stored Communications Act (SCA), by Jimmy Balser (2022).

Does a Geofence Warrant Satisfy the Requirements of the Fourth Amendment?
When the collection of geofence data is considered to constitute a search, “it follows that the
government must generally obtain a warrant supported by probable cause and particularity before
requesting such information.”129 Warrants may lack sufficient probable cause or particularity if
they amount to a “general” warrant, which “specif[ies] only an offense, leaving to the discretion
of the executing officials the decision as to which persons should be arrested and which places
should be searched.”130 General warrants are “plainly unconstitutional” and their historic use in
England served as a primary impetus for the Fourth Amendment.131
Caselaw is still developing on whether geofence warrants can satisfy Fourth Amendment
particularity and probable cause requirements. The original Fourth Circuit panel in Chatrie, and
the subsequent en banc court, did not reach this question (although, as noted above, several
members of the en banc court expressed skepticism that geofence warrants could).132 As
discussed below, the Supreme Court’s Chatrie decision also did not reach the question. The Fifth
Circuit held in Smith that the geofence warrant in that case amounted to a “general” warrant
prohibited by the Fourth Amendment.133 The recipient of such a warrant, the Smith court
observed, must search “its entire database” to arrive at the sample of data that is actually sought
124 S. REP. NO. 99-541, at 3 (1986).
125 See Balser, supra note 123.
126 18 U.S.C. § 2703.
127 Brief for Google LLC as Amicus Curiae in Support of Neither Party Concerning Defendant’s Motion to Suppress

Evidence from a “Geofence” General Warrant at 4, United States v. Chatrie, 590 F. Supp. 3d 901 (E.D. Va. 2022) (No.
3:19-cr-130), 2019 WL 8227162.
128 E.g., In re Search of Info. that is Stored at Premises Controlled by Google, No. 2:22-MJ-01325, 2023 WL 2236493
at *5 (S.D. Tex. Feb. 14, 2023); Affidavit in Support of Search Warrant Application at 8, United States v. Smith, No.
21-CR-00107 (N.D. Miss. Feb. 10, 2023), Dkt. No. 74-2; but cf. Affidavit for Search Warrant, United States v. Chatrie,
590 F. Supp. 3d 901 (E.D. Va. 2022) (No. 3:19-CR-00130), Dkt. No. 54-1 (arguing in affidavit that there was probable
cause to issue geofence warrant to Google under Virginia state law).
129 United States v. Smith, 110 F.4th 817, 836 (5th Cir. 2024), cert. denied, 146 S. Ct. 356 (2025).
130 Id.
131 Id.; see also Stanford v. Texas, 379 U.S. 476, 482 (1965) (providing historical account).
132 United States v. Chatrie, 107 F.4th 319, 324 (4th Cir. 2024), aff’d en banc, 136 F.4th 100 (4th Cir. 2025) (per
curiam), cert. granted in part, No. 25-112, 2026 WL 120676 (U.S. Jan. 16, 2026).
133 Smith, 110 F.4th at 824.

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by law enforcement.134 Given that Google’s review entails a search of all 592 million individual
accounts with Location History enabled, the Fifth Circuit determined that it amounts to “the exact
sort of general, exploratory rummaging that the Fourth Amendment was designed to prevent.”135
This review, the court held, occurs while law enforcement has “no idea who they are looking for,
or whether the search will even turn up a result.”136 The Fifth Circuit further opined that the
“quintessential problem” with geofence warrants is that they do not include sufficiently particular
information, such as a specific user to be identified;137 rather, they identify only a temporal and
geographic location where a person of interest may turn up. Rejecting the government’s claim that
geofence warrants are sufficiently “limited to specified information directly tied to a particular
[crime] at a particular place and time,” the Smith court stated that, although the results of a
geofence warrant may be sufficiently narrowly tailored as to assuage Fourth Amendment
concerns, the search itself is not.138 In other words, the court held that during the three-step
process of reviewing, collecting, and turning over to law enforcement the requested geofence
data, the warrant fails at the very first step by allowing law enforcement—albeit through
Google—to “rummage through troves of location data from hundreds of millions of Google users
without any description of the particular suspect or suspects to be found.”139
A few state courts of last resort have taken a different approach than the Fifth Circuit in analyzing
reverse warrants.140 One of those cases, People v. Seymour,141 which involved a keyword warrant,
is discussed following the next section on the Supreme Court’s recent decision in Chatrie.

The Supreme Court’s Decision in Chatrie
Because a majority of the en banc court in the Fourth Circuit did not resolve the question of
whether a geofence search is a Fourth Amendment search, the circuit split that had emerged
between the Fourth and Fifth Circuits appeared to have abated. Still, the numerous, varied
opinions from the en banc court may have, at least in part, given rise to the Supreme Court’s
consideration of the case.142 On January 16, 2026, the Supreme Court granted certiorari in Chatrie
134 Id. at 837.
135 Id.
136 Id.
137 Id.
138 Id.
139 Id. at 837–38.
140 See, e.g., Jones v. State, 913 S.E.2d 700, 711 (Ga. 2025) (holding that probable cause supported issuance of a

geofence warrant, that the warrant was sufficiently particular, and that the first and second steps in the execution of a
geofence warrant do not amount to “general rummaging”); cf. Wells v. State, 714 S.W.3d 614, 625 (Tex. Crim. App.
2025), reh’g denied, No. PD-0669-23, 2025 WL 1699563 (Tex. Crim. App. June 18, 2025) (Yeary, J., announcing
judgment of the court) (assuming that a warrant was required and determining that there was probable cause for a
geofence warrant and that it “provided sufficient particularity with respect to both the ‘place to be searched’ and the
‘things to be seized.’”).
141 536 P.3d 1260 (Colo. 2023).
142 Further illustration of judicial disagreement on this issue may be found in Wells v. State, 714 S.W.3d 614, 624 (Tex.
Crim. App. 2025), reh’g denied, No. PD-0669-23, 2025 WL 1699563 (Tex. Crim. App. June 18, 2025). There, two
judges would have held that a geofence warrant did not violate the Fourth Amendment because there was no reasonable
expectation of privacy in Location History due to the third-party doctrine. Id. at 626–27 (Finley, J., concurring). Three
other judges would have held that there was no “legitimate expectation of privacy in the limited information sought
through the geofence warrant’s first and second steps” but that there was such an expectation “in the information
sought by the warrant’s third step, which included six months of prior IP history.” Id. at 626 (Newell, J., concurring in
part and dissenting in part). Further compounding the disagreement, in the opinion announcing the judgment of the
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to consider whether the execution of the geofence warrant violated the Fourth Amendment.143 The
Court declined to consider a second question regarding the applicability of the exclusionary rule
to evidence obtained through the geofence warrant.144 Oral arguments were held on April 27,
2026, and the Court issued its opinion on June 29, 2026.145
A majority of the Court held that an individual has a reasonable expectation of privacy in their
Location History and that law enforcement does, therefore, conduct a search when it gains access
to that data for purposes of the Fourth Amendment.146 The Court declined to consider whether the
warrant in the instant case was reasonable, remanding to the Fourth Circuit for consideration the
question as to whether the warrant was supported by probable cause and described with sufficient
particularity at each stage of the search process.147
The controlling opinion, written by Justice Elana Kagan and joined by four other Justices,
anchored its reasoning largely in the conclusions reached in Carpenter.148 “The resemblances
between CSLI and Location History, in their relationship to personal privacy,” the Court wrote,
“practically leap off the page.”149 The Court continued: “Everything Carpenter relied on to find
that law enforcement officers conducted a Fourth Amendment search when they accessed
wireless carriers’ CSLI records applies as well or better to the police’s accessing of Google’s
Location History data.”150 The Court offered that Location History provides greater granularity of
a person’s movements than does CSLI, and that, like with CSLI, law enforcement can
“reconstruct retrospectively” those movements.151 Location History, the Court reasoned, also
implicates privacy interests more than CSLI because Location History “is more the individual’s
own”—meaning individuals utilize their Location History far more often than one would their
CSLI records.152 The Court also rejected the government’s arguments, first that the short
time frame of data sought by law enforcement immunized its efforts from Fourth Amendment
scrutiny, explaining “we have never understood Fourth Amendment protections as kicking in only
once an intrusion ‘goes too far,’”153 and second, that the third-party doctrine applied in this case,
noting that “no good reason exists to reach a different result” on that question than was reached in
Carpenter.154 As mentioned, the Court left to the Fourth Circuit the question of whether the
search undertaken was reasonable.155
Justice Ketanji Brown Jackson, joined by Justice Sonia Sotomayor, concurred but wrote
separately to say that beyond the majority’s conclusion that a search was conducted, she would
court, four judges assumed that the Fourth Amendment “generally requires police to obtain a search warrant for
corporate-held location history data,” and the judges focused on whether the warrant was supported by probable cause
and particularity, as discussed below.
143 United States v. Chatrie, 136 F.4th 100 (4th Cir. 2025), cert. granted in part, No. 25-112, 2026 WL 120676 (U.S.
Jan. 16, 2026).
144 Order Granting Certiorari in Part, Chatrie v. United States, No. 25-112, 2026 WL 120676 (U.S. Jan. 16, 2026).
145 Chatrie v. United States, 146 S. Ct. 2193 (2026).
146 Id. at 2199.
147 Id. at 2199-2200.
148 Id. at 2199.
149 Id. at 2207-08.
150 Id. at 2208.
151 Id. (alterations omitted).
152 Id. at 2208-09.
153
Id. at 2210 (citing Pennsylvania Coal Co. v. Mahon, 260 U.S. 393, 415 (1922)).
154 Id. at 2212.
155 Id. at 2215-16.

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have found that the “search violated the Fourth Amendment.”156 This is so, she argued, because
both “the second and third stages157 of the search process here did not” meet the probable cause
requirement.158
Justice Neil Gorsuch, concurring in the judgment, wrote separately to advocate for a holding that
does not rely on the “reasonable expectation of privacy” test first outlined in Katz v. United
States—a test he found to be, though a “familiar feature of our law . . . no more persuasive for
it.”159 Instead, Justice Gorsuch would favor a test that focuses directly on whether an individual’s
“person, house, papers, [or] effects” have been subject to an unreasonable search.160 Justice
Gorsuch would have ruled that a search had occurred under a “more traditional Fourth
Amendment argument[],” because Chatrie’s Location History “qualifies as his personal property”
and therefore may be considered among his “effects.”161
Three Justices dissented. Justice Samuel Alito, joined by Justice Clarence Thomas, argued that
the Court erred in the first instance in granting certiorari given the posture of the case, claiming
the decision amounts to an advisory opinion because “nothing in today’s decision bears on the
Fourth Circuit’s good-faith holding,” and therefore it will not have “any impact . . . on the Fourth
Circuit’s judgment.”162 Moreover, he wrote, Google’s change in policy that it now stores Location
History not on their servers but on individual users’ devices, renders the issue of “scarcely any
ongoing significance,” and because the “Court has long been averse to granting certiorari on
questions ‘that time [will] soon bury,’” the case did not meet the Court’s “prudential certiorari
considerations.”163
Justice Alito further wrote that Chatrie could not establish that the police “transgressed any rights
in his papers or effects . . . under traditional search-and-seizure principles.”164 Decrying the
Court’s “repudiat[ion] [of] the boundary lines that Carpenter drew to distinguish its novel holding
from longstanding doctrine,” Justice Alito asserted that the Court effectively “announce[d] a new
rule of Fourth Amendment law: The police must obtain a warrant every time they access any cellphone location information from a third party, however brief the duration, however innocuous the
request, and however voluntarily that information was disclosed by the user.”165 The majority’s
decision, Justice Alito continued, also “creates its own share of line-drawing problems,” beyond
those created by what he asserts was “the inevitable byproduct [of] Carpenter.”166 Moreover, he
wrote, the majority’s decision casts doubt upon “the boundary between Carpenter and the thirdparty doctrine.”167
Joined by Justice Amy Coney Barrett, Justice Alito also “contrast[ed] the Court’s modesty” in
extending the “expectation of privacy” test in the years following Katz with what he called
156 Id. at 2217 (Jackson, J., concurring).
157 See supra “Google’s Policies and Procedures Regarding Geofence Warrants.”
158 Chatrie, 146 S. Ct. at 2217.
159 Id. at 2218 (Gorsuch, J., concurring).
160 Id.
161 Id. at 2220. The Fourth Amendment guarantees “The right of the people to be secure in their persons, houses,

papers, and effects, against unreasonable searches and seizures.” U.S. CONST. amend. IX.
162 Chatrie, 146 S. Ct. at 2224 (Alito, J., dissenting).
163 Id. at 2225-26 (quoting Darr v. Burford, 339 U.S. 200, 227 (1950) (Frankfurter, J., dissenting)).
164 Id. at 2227.
165
Id. at 2232 (emphasis in original).
166 Id. at 2233.
167 Id.

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Chatrie’s “maximalist extension of Carpenter.”168 On “the criteria that Carpenter found relevant
in determining whether to apply the third-party doctrine,” he wrote, “Chatrie has a far lesser
privacy interest in the data” that was sought by law enforcement.169 The third-party doctrine,
Justice Alito maintained, thus foreclosed Chatrie’s reasonable expectation of privacy, owing to his
sharing his Location History information with Google.170
Finally, Justice Barrett also wrote separately to expressly state that, while she agrees that Chatrie
had “no reasonable expectation of privacy in data . . . that he voluntarily disclosed to Google,”
she does not “quarrel with” Carpenter or the decision to grant certiorari in Chatrie.171

Keyword Warrants
One legal scholar has characterized keyword warrants—sometimes referred to as “reversekeyword warrants”172—as essentially “revers[ing]” the typical process by which law enforcement
secures information about a suspect in a crime.173 Like geofence warrants, keyword warrants
begin with law enforcement identifying something they “think could be evidence”174—such as, in
the case of geofence warrants, a location at a particular time, or in the case of keyword warrants,
“a search of a particular address that was later burglarized.”175 For example, if a home located at
123 Main Street is burglarized, law enforcement may seek a keyword warrant to collect a list of
search engine users who searched that address in the days prior to the burglary occurring. Law
enforcement may use keyword warrants in an attempt to seek other information, too, such as the
identity of users who searched for a particular person against whom a crime was later committed.
Some courts have examined the use of keyword warrants by law enforcement. In People v.
Seymour,176 the Colorado Supreme Court explained, “[Keyword] warrants start with a potentially
incriminating piece of evidence—a search term like the address where [a crime] occurred—then
request a list of users implicated by that evidence.”177 Although such warrants seek search terms
rather than location data, they are still conceptually similar to geofence warrants in that neither
follows the traditional process of “first identify[ing] a suspect or suspects, then obtain[ing] a
warrant to search them or their property for evidence.”178

168 Id. at 2228 n.3.
169 Id. at 2232.
170 Id.
171 Id. at 2234 (Barrett, J., dissenting).
172 See supra note 10 (discussing the terminology used to describe these types of warrants).
173 Brian L. Owsley, Searching a Person’s Thoughts: Keyword Search Warrants and Fourth Amendment Concerns, 28

STAN. TECH. L. REV. 66, 69 (2025).
174 Id.
175 Id.
176
Seymour, 536 P.3d at 1260.
177 Id. at 1268 n.1.
178 United States v. Smith, 110 F.4th, 817, 822 (5th Cir. 2024); Seymour, 536 P.3d at 1268 n.1.

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Policies and Procedures
To date, the majority of keyword warrant cases have involved Google.179 As is the case with
geofence warrants, Google has established a process by which it responds to keyword warrants.180
Upon receiving a keyword warrant, Google employees “formulate[] a text-based query matching
the warrant’s specifications” (e.g., “123 Main Street”), which is then “run against billions of daily
search records from Google Search and Google Maps.”181 Google then creates a file of the
matches resulting from the search and includes records that are “exact matches, or, more
commonly, ‘the results may extend to queries that include the specified search terms as part of a
query that contains other words.’”182 For example, if the specified search term is “123 Main
Street,” Google’s search might return queries such as “condos at 123 Main Street” or “who lives
at 123 Main Street, Springfield.” Google then anonymizes the information by removing account
identifiers prior to turning the file over to law enforcement, which can then review the file by
categories including, for example, the actual search query, the date and time of the search, the
approximate location from which the search was conducted, and the search results obtained by
the user.183 From there, law enforcement will review the anonymized data to determine which
results, if any, may be relevant to their investigation (for example, law enforcement may isolate
the results occurring only during a specific time frame) and exclude those that are not relevant.184
At this stage, Google may reveal the identities of the users sought, or law enforcement may need
to obtain a second search warrant if the original warrant does not authorize law enforcement to
obtain identifying data.185

Constitutionality of Keyword Warrants
Given the novelty of keyword warrants, even less caselaw exists regarding their constitutionality
than that of geofence warrants.186 Two state court cases, however, offer what appear to be
divergent views on the issue.
In People v. Seymour,187 which involved a fatal residential arson, law enforcement obtained
information from Google about five internet protocol (IP) addresses that were associated with
devices that had searched the location of the fire in the two-week period prior.188 To do so, law
179 See infra “Constitutionality of Keyword Warrants.”
180 Google reportedly “processes approximately 400 reverse-keyword warrants per year.” In re Ct. Ord. for Prod. of

Recs. to Google, LLC, No. 2024-cv-30942, 2024 WL 5314970, at *1 (Colo. Dist. Ct. Dec. 6, 2024).
181 Owsley, supra note 173, at 69–70 (quoting Declaration of Nikki Adeli ¶ 4, Colorado v. Gavin Seymour, No. 21-cr20001 (Colo. Dist. Ct. July 5, 2022) [hereinafter Adeli Decl.]).
182 Id. at 70 (quoting Adeli Decl. ¶ 6).
183 Id. (citing Adeli Decl. ¶ 7).
184 Id. at 71 (citing Adeli Decl. ¶ 8).
185 Id. (citing Adeli Decl. ¶ 9).
186 See People v. Seymour, 536 P.3d 1260, 1269–70 (“The constitutionality of reverse-keyword warrants presents an
issue of first impression in Colorado. Indeed, to our knowledge, no state supreme court or federal appellate court has
addressed the constitutionality of such warrants.”). But see, e.g., In re Court Order for Production of Records to
Google, LLC, No. 2024-cv-30942, 2024 WL 5314970 (Colo. Dist. Ct. Dec. 6, 2024) (granting in part Google’s motion
to quash a keyword warrant on grounds that it imposed an undue burden on the company and violated the Stored
Communications Act); Owsley, supra note 173, at 72–73 (discussing example of a case where law enforcement may
seek information using a keyword warrant); id. at 76 (discussing example of a case where law enforcement utilized
results gathered from a keyword search warrant to identify and charge a defendant with arson outside the home of a
witness in a criminal trial).
187 536 P.3d 1260.
188 Id. at 1269.

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enforcement used a series of warrants to navigate Google’s “staged process to respond to
warrants,”189 described above. The Colorado Supreme Court concluded that the keyword warrant
amounted to a search under the Colorado State Constitution and went on to examine whether such
warrants are unconstitutional general warrants.190 The Seymour court rejected the defendant’s
contention that, because the “place to be searched” was Google’s entire database, the warrant was
necessarily overbroad and explained that the “ultimate touchstone” of an analysis of the legality
of a warrant is “reasonableness.”191 It found the scope of the place to be searched reasonable
“when we consider the filter provided by the search parameters set forth in the warrant.”192 This,
the court concluded, “dramatically reduce[d] the intrusiveness of the search.”193 Of potential
significance, the court discounted the idea that a warrant necessarily lacks particularity simply
because of the size of the search area.194
Commonwealth v. Kurtz,195 on the other hand, involved the prosecution of an individual for rape
and kidnapping.196 Law enforcement executed a keyword warrant on Google for a report of any
IP addresses that had searched the victim’s address within a week of the crime.197 This led law
enforcement to the defendant who was prosecuted and who challenged the validity of the warrant
on appeal.198 The opinion199 concluded that the “average search engine user” lacks “an
expectation of privacy in the records generated” by “general, unprotected internet searches.”200
That included the defendant’s Google searches for the victim’s home address.201 Therefore, the

189 Id. at 1268; see also id. at 1268 n.1 (describing typical reverse-keyword warrant).
190 Id. at 1272.
191 Id. at 1275.
192 Id.
193 Id.
194 Id. at 1275 (explaining that “‘the scope of a lawful search is “defined by the object of the searches and the places in

which there is probable cause to believe that it may be found”’” (quoting Maryland v. Garrison, 480 U.S. 79, 84
(1987))). The court also emphasized that a search is not unconstitutional simply because law enforcement “cursorily
examines unrelated documents,” explaining that such incidental examinations are unavoidable, even in cases “when a
warrant is adequately particularized,” in order “‘to determine whether [the unrelated documents] are, in fact, among
those papers authorized to be seized.’” Id. at 1276 (quoting Andresen v. Maryland, 427 U.S. 463, 482 n.11 (1976)).
One observer has suggested that Seymour, while standing for the proposition that such warrants are not per se
unconstitutional, may have a potentially “limiting effect” on future uses of keyword search warrants by law
enforcement, at least in Colorado, as it makes clear that law enforcement must provide sufficient particularity to justify
the warrant. See Owsley, supra note 173, at 79.
195 Nos. 98 MAP 2023, 99 MAP 2023, 100 MAP 2023, 2025 WL 3670767, at *1, 11–12 (Pa. Dec. 16, 2025), aff’g, 294
A.3d 509 (Pa. Super. Ct. 2023). The Superior Court in Kurtz also determined that the defendant enjoyed no legitimate
expectation of privacy over data produced in a tower dump by AT&T. See supra note 57.
196 Id. at *1.
197 Id. at *3.
198 Id.
199 Three of the Pennsylvania Supreme Court’s seven justices signed on to the Opinion Announcing the Judgment of
the Court. Three justices concurred in the judgment but would not have reached the question of whether there was a
search, because there was a warrant supported by probable cause. 2025 WL 3670767, at *15–19. One of those
concurring justices wrote separately as well, finding that “reaching the constitutional issue” was not necessary to
resolution of the appeal, but nevertheless determining that if reaching the constitutional issue were required, she would
agree that “‘the average search engine user’ does not have ‘an expectation of privacy in the records generated by
unprotected internet searches.’” Id. at *19–20 (Mundy, J., concurring). One justice dissented. Id. at *20. For brevity,
the Opinion Announcing the Judgment of the Court is referred to herein as the “opinion.”
200 Id. at *1, 11–12.
201 Id. at *1.

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opinion did not reach the defendant’s challenge that the warrant was lacking in “probable cause
individualized to him.”202
In concluding that the defendant enjoyed no reasonable expectation of privacy in his Google
searches, the Kurtz opinion turned to Carpenter’s voluntariness analysis.203 On those grounds, the
opinion found Google searches as distinguishable from the cell-phone derived long-term CSLI at
issue in Carpenter.204 According to the opinion, a “cell phone user . . . cannot avoid creation of a
data trail,” but an “internet user can avoid or minimize the creation of such records by using other
methods,” such as making restaurant reservations in person or over the phone, conducting
research through “print materials at the library,” or shielding browsing history.205 The opinion
determined that every time a user “type[s] terms into a search engine and hit[s] the ‘Enter’ key,” it
represents a voluntary choice by a user to “transmit data to a third party.”206 The opinion also
concluded that the terms of Google’s policies further diminish a user’s reasonable expectation of
privacy.207 As a result, “for purposes of federal law, the traditional third-party doctrine applies.”208

Congressional Considerations
Although the Supreme Court has now determined that accessing geofence data does constitute a
search, the Court remanded to the Fourth Circuit the question of whether the warrant issued in
Chatrie was sufficient to satisfy Fourth Amendment protections. Uncertainty also persists
regarding the various views of the different state courts209 and whether Chatrie’s holding is
applicable to keyword searches.
State legislatures have also taken an interest in reverse warrants. At least one state, Utah, has
restricted the use of geofence data by law enforcement by enacting a law that generally requires
investigators to obtain a search warrant for geofence data.210 Utah has also enacted legislation
restricting the use of keyword warrants.211 Some other state legislatures have considered similar
geofence and keyword warrant proposals.212 Another approach, adopted by at least one state,213
restricts the practice of private entities establishing geofences around health care facilities.214
At the federal level, reverse warrants have been the subject of congressional testimony.215 Several
Members of Congress sent a letter to Google in 2022 warning of the potential use of geofence
202 Id.
203 Id. at *10–12; see supra text accompanying note 44.
204 2025 WL 3670767, at *10–12.
205 Id.
206 Id. at *10.
207 Id.
208 Id. at *12.
209 See, e.g., discussion on opinions of the state courts of Texas and Georgia supra note 140.
210 UTAH CODE ANN. § 77-23f-102 (2025).
211 Id. § 77-23f-102.2 (2025).
212 E.g., S.B. 49, 2025–2026 Leg. Sess. (Vt. 2025); A.B. 407/S.B. 404, 2025–2026 Leg. Sess. (N.Y. 2025); H.B. 2791,

102d Gen. Assemb., 2d Reg. Sess. (Mo. 2024); H.B. 145, 153d Gen. Assemb. (Del. 2024); A.B. 793, 2023–2024 Reg.
Sess. (Cal. 2023).
213 S.B. 49, 2025–2026 Leg. Sess. (Vt. 2025).
214 E.g., WASH. REV. CODE § 19.373.080 (2023).
215 See A Continued Pattern of Government Surveillance of U.S. Citizens: Hearing Before the H. Comm. on the
Judiciary, Subcomm. on Crime and Fed. Gov. Surveillance, 119th Cong. 7 (2025) (statement of Kia Hamadanchy,
Senior Policy Counsel, ACLU) (discussing reverse warrants).

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warrants in abortion investigations and asking the company to minimize its data collection
practices.216 In 2023, the Chairman of the House Judiciary Committee sent a letter to the U.S.
Attorney General seeking information on the use of geofence warrants in January 6th
investigations and in other instances.217
Although Congress would likely be found to have exceeded its authority in instructing the courts
in how to interpret the Fourth Amendment, Congress could explore restrictions on federal law
enforcement’s use of reverse warrants or add additional statutory privacy protections for location
information, search terms, or IP address data akin to those contained in the SCA for
communications (particularly if courts ultimately reach and reject Google’s position that the
provisions requiring a warrant in the SCA already independently protect Location History
information).218 Alternatively, Congress may seek to codify the policies and procedures that
Google has established for responding to reverse warrants, and it may codify them exactly or
make the required process either more strict or more lenient. For example, Congress could require
that law enforcement obtain a second warrant prior to the third step of deanonymizing the
requested data, rather than relying on the initial warrant.219 The Fourth Circuit’s ultimate decision
in Chatrie upon remand as to whether the warrant issued was supported by probable cause and
described with sufficient particularity at each stage of the search process may further inform
potential avenues of reform for Congress to consider.

216 Press Release, Alex Padilla, supra note 20.
217 Letter from Rep. Jim Jordan, supra note 20.
218 See Dickerson v. United States, 530 U.S. 428, 437 (2000) (“But Congress may not legislatively supersede our

decisions interpreting and applying the Constitution.”).
219 As discussed above, at least one state jurisdiction seems to already require such a step. See supra note 91 and
accompanying text.

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Table 3. Selected CRS Products on the Fourth Amendment,
Technology, and Related Topics
•

CRS Legal Sidebar LSB11274, Geofence Warrants and the Fourth Amendment: The Supreme Court Weighs In, by
Clay Wild (2026)

•

CRS Legal Sidebar LSB11339, Advances in DNA Analysis: Fourth Amendment Implications, by Peter G. Berris
(2025)

•

CRS In Focus IF13068, Automated License Plate Readers: Background and Legal Issues, by Peter G. Berris, Kristin
Finklea, and Dave S. Sidhu (2025)

•

CRS Legal Sidebar LSB11336, Excessive Force and the Fourth Amendment: Supreme Court Clarifies Scope of Legal
Test, by Michael A. Foster and Dave S. Sidhu (2025)

•

CRS Report R48160, Law Enforcement and Technology: Use of Automated License Plate Readers, by Kristin Finklea
(2024)

•

CRS Legal Sidebar LSB11165, Disrupting Botnets: An Overview of Seizure Warrants and Other Legal Tools, by Peter
G. Berris (2024)

•

CRS Legal Sidebar LSB10801, Overview of Governmental Action Under the Stored Communications Act (SCA), by
Jimmy Balser (2022)

•

CRS Legal Sidebar LSB10786, Abortion, Data Privacy, and Law Enforcement Access: A Legal Overview, by Chris D.
Linebaugh (2022)

•

CRS Legal Sidebar LSB10713, The Fourth Amendment and the Internet: Legal Limits on Digital Searches for Child
Sexual Abuse Material (CSAM), by Michael A. Foster (2022)

•

CRS Legal Sidebar LSB10552, Torres v. Madrid: Police Use of Force, Fourth Amendment Seizures, and Fleeing
Suspects, by Peter G. Berris (2021)

•

CRS Legal Sidebar LSB10387, Do Warrantless Searches of Electronic Devices at the Border Violate the Fourth
Amendment?, by Hillel R. Smith (2021)

Author Information
Clay Wild
Legislative Attorney

Acknowledgments
Former CRS Legislative Attorney Peter Berris coauthored an earlier version of this product.

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Disclaimer
This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan
shared staff to congressional committees and Members of Congress. It operates solely at the behest of and
under the direction of Congress. Information in a CRS Report should not be relied upon for purposes other
than public understanding of information that has been provided by CRS to Members of Congress in
connection with CRS’s institutional role. CRS Reports, as a work of the United States Government, are not
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copy or otherwise use copyrighted material.

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R48852 · VERSION 3 · UPDATED

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/crs%3AR48852. Public record. Not legal advice.