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

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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Reverse Warrants and the Fourth Amendment

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.

Congressional Research Service

R48852 · VERSION 3 · UPDATED

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