Mapping the Future of Surveillance: Geofence Warrants and the Risks of Chatrie

In the last two years of rapid changes in technology and U.S. politics, the circumstances in which the government and law enforcement may access personal digital data have risen to the national spotlight and prompted privacy concerns. This is exemplified by the case United States v. Chatrie (4th Cir. 2024). United States v. Chatrie ruled that a geofence warrant was not a Fourth Amendment search. The case is currently awaiting approval for escalation to the Supreme Court. [1] The Fourth Amendment protects the right to privacy by outlawing unreasonable searches of an individual and their effects, and requiring probable cause and particularity for legal search warrants. [2] Geofence warrants, which authorize the combing of location data for all mobile devices within a specific geographical and temporal frame, are particularly liable to infringing on privacy rights. Thus, geofences should fall under the purview of the Fourth Amendment. Based on United States v. Carpenter (2018) and United States v. Smith (5th Cir. 2024), Chatrie’s ruling is unconstitutional under the Fourth Amendment. The risks of reliance on geofence warrants as deregulated technology risks warrant abuses and extreme violations of privacy; they should, therefore, be outlawed under the Fourth Amendment.

In May 2019, an armed man robbed a bank in Midlothian, Virginia. [3] After viewing surveillance footage that showed the man holding a cell phone, police were able to use ownership of a cell phone as evidence to request a geofence warrant that was approved by a state magistrate judge. The police asked for data corresponding to 150 meters around the bank within a half-hour of the robbery. [4] 

Law enforcement went through three rounds of geofence warrants, per Google’s three-round procedure. Chatrie’s warrant first returned 19 anonymized individuals. Police then requested an expanded timeframe for nine and tracked their data within a two-hour timeframe, removing geographical limitations. Finally, police asked for detailed information for three Google accounts, including names, email addresses, subscriber information and phone numbers. [5] After police combed through non-Google databases and connected one person’s location to the bank and his name to a residence he appeared to flee to shortly after, Okello Chatrie was arrested in September 2019 and sentenced to 141 months’ imprisonment by the U.S. District Court for the Eastern District of Virginia in August 2022. [6] The case was shortly escalated to the Fourth Circuit, as Chatrie challenged the constitutionality of his geofence, arguing that it violated the Fourth Amendment.

An escalation to the Fourth Circuit, in United States v. Chatrie (4th Cir. 2024), however, avoided directly addressing the Fourth Amendment. [7] Instead, they used the third-party doctrine, which states that an individual cannot have an expectation of privacy in information that is voluntarily provided to others. The court argued that Chatrie voluntarily exposed his information to Google, a third party, and thus the police did not conduct a Fourth Amendment search. The breadth of divisive opinions on the topic led to an en banc—all judges of the Fourth Circuit hearing a case instead of a single judge or panel. On April 30, 2025, the Fourth Circuit issued an anonymous per curiam opinion affirming the district court’s judgment, but containing various dissenting opinions on the validity of the geofence warrant, speaking to its controversiality. [8] 

Chatrie’s case and the shifting legal territory under it raises two prescient questions: whether the execution of the geofence warrant counted as a search, and whether that search violated the Fourth Amendment.

Chatrie should have used United States v. Carpenter (2018), one of the landmark cases in the Fourth Amendment’s application to technology, as case precedent. Carpenter was a defining case for Fourth Amendment interpretation for location-based technology, where the Supreme Court affirmed that tracking location data over multiple days was a Fourth Amendment violation. They rejected third-party doctrine by affirming that having a cellphone is a requirement of participation in modern society—that there is a “world of difference between the limited types of personal information” that was addressed in past third-party doctrine precedent and the “exhaustive chronicle of location information casually collected by wireless carriers today.” [9] This applies to Chatrie as well, where application of an outdated third-party doctrine permitted access to exhaustive information on potentially unlimited amounts of people. Chatrie thus should have ruled that geofence warrants, as a novel technology, counted under the Fourth Amendment. 

Law enforcement’s case in Chatrie rested on one tenuous fact, namely that Google’s collection of location data history is opt-in. [10] At a glance, this would seem to indicate that Chatrie shared his location information with a third party of his own volition. However, cellphone users face immense everyday pressure to ‘opt-in’ to share private information with corporations, and the process is frictionless by design. Users are prompted to opt-in to Google’s Location History both when installing an app and repeatedly across multiple apps. [11] When Google gave privacy warnings, they were “limited,” “partially hidden,” and “less than pellucid.” [12] Chatrie was not informed by the Google pop-up that stopping location tracking only “paused” it; nor was he informed of how precise Location History can be before being able to press the opt-in button. [13] It is in Google’s interest to protect its users’ privacy and consequently promote its services as safe and reliable. Nonetheless, Google has an incentive to obscure the extent of its data collection, in order to promote use of their products such as Google Maps, leading to opaque and deceptive privacy practices that consumers generally cannot not knowingly or wholly consent to. 

Carpenter comments exactly that the exposure of location data from modern cell phones may not be meaningfully voluntary, since the user does not truly expose their data meaningfully voluntarily even if they “‘assume the risk’ of turning over a comprehensive dossier of his physical movements.” [14] Thus, Chatrie did not consent wholly voluntarily and in full knowledge to what location sharing would entail. Under Carpenter, Chatrie should not have assumed third-party doctrine and, therefore, the geofence warrant was indeed a search. 

Taking that geofences are a Fourth Amendment search, applying Fourth Amendment search requirements reveals that a geofence warrant is not particular enough to be a constitutional warrant. By nature they cannot be perfectly precise, nor can they be constrained to access a limited number of innocent bystanders’ locations. In other words, their search potential is limitless. Because Google estimates location data (aiming for a 68% confidence interval), it is possible for geofences to return false negatives and, more concerningly, false positives, where someone not within the particular confines of a geofence may be reported as inside it. [15] In Chatrie, one such false positive was likely captured. During the second round of the geofence warrant, one of the nine requested individuals appeared in original geographical boundaries about seventeen minutes before the robbery occurred. Based on the small amount of time they appeared in the geofence boundaries, however, they were likely driving on another street at the time and only appeared in the geographical boundaries briefly. Spencer McInvaille, Digital Forensic Examiner, testified that he may not have stepped foot within the original geofence at all. [16] Despite the fact that police officers attempted to request a particular 150-meter radius around the bank, the nature of geofence warrants meant the requirement could not be followed. This offends particularity, as the execution of the warrant failed to seek out data merely within the bounds of its particular parameters. 

A more recent geofence warrant case has also opened a circuit split between the Fourth and Fifth Circuits. Notably, in August of 2024 the Fifth Circuit ruled in United States vs. Smith (5th Cir. 2024) that, in a break with Chatrie, that geofence warrants are "categorically prohibited by the Fourth Amendment" insofar as they present the exact sort of “‘general, exploratory rummaging’ that the Fourth Amendment was designed to prevent.” [17] Smith was an extraordinarily similar case to Chatrie: both were a case of robbery where a district court denied a motion to suppress, both defendants appealed, and both circuit courts were called to determine the constitutionality of Google’s geofence warrants. The Fifth Circuit made frequent reference to the Fourth Circuit in its final ruling, explicitly rejecting Chatrie’s case that brief amounts of location history are not overly revealing, and arguing that geofence warrants are overbroad because they search Google’s entire database of all accounts in order to return specific geofence parameters. However, Smith makes the distinction that geofence warrants are only prohibited in the specific circumstances of its case: when law-enforcement obtains a geofence warrant to compel a tech company (such as Google) to search through its entire historical location database for all devices present in a defined geographic area and during a defined time without specifying particular suspects. [18] This not only leads to a circuit split with Chatrie, which contains the exact scenario, but also lends itself to ambiguity in how geofence warrants may apply outside these circumstances or Google’s specific process, opening the possibility for ill-defined warrant abuses nationwide. A Supreme Court ruling could therefore reconcile the unstable legal split and establish geofence warrant case law. 

That is not to say that other intermediate and extrajudicial processors of warrants, such as Google, have not been adapting their privacy policies. In the immediate aftermath of Chatrie, however, Google started to increase its privacy protections. In June 2020, Google made auto-deleting their data an automatic feature for those turning on Location History for the first time. [19] In December 2023, Google migrated location history data to users’ personal devices instead of their database, which means that it can no longer turn over location data without law enforcement first identifying a specific person and device. [20] Over the course of a year, Google gradually migrated its data, and it now automatically sets to auto-delete. Google, one of the primary responders to geofence warrants, has responded to the clear unlimited and unconstitutional nature of geofence warrants. 

It speaks to the regulatory weaknesses in technology, however, that it is Google themselves improving their privacy policies. Corporations do not have the power to determine constitutionality. Section 18 of US Code § 3105 requires the officer to be “present and acting in [a warrant’s] execution,” [21] and allowing corporations to assess the legalities of a warrant and formulate a response independent of court approval or officer oversight in the first place violated this. 

The restrictions on accessing Google’s location data means that law enforcement are now turning to different contractors—with even more deregulated policies than Google. In early 2024, Forbes reported that law enforcement have turned to telecom companies such as AT&T or T-Mobile to provide location history for police investigations. Mobile data towers, with an accuracy range of 50-500 meters, have much worse location accuracy triangulation than Google’s 2-5 meter range. [22] A Wisconsin police officer noted that location data from mobile data companies could be off by anywhere between “a few square blocks to several square miles.” [23] Chatrie already led to confusion over what people were within search warrant, something that will only worsen by using mobile data towers. Reliance on less accurate telecom data further risks the data of innocent people in criminal investigations and violates the Fourth Amendment protection against unreasonable searches. 

Amid growing concerns over surveillance from both corporations and the state, Chatrie cannot constitutionally remain in split with the Fifth Circuit’s Smith ruling. It becomes clear that the use of data for surveillance in Chatrie has nationwide implications for the future of privacy protections. While persecuting criminals is to the obvious benefit of society, warrants seeking digital personal information can be an insidiously slippery slope. In the future, the same geofence warrants that track down lawbreakers may rebound and be used to persecute civilians such as protesters, violating both the Fourth and First Amendments. In line with the issues surrounding telecom providers, the ACLU of Florida accused law enforcement as early as 2014 of concealing from court files the use of mobile data towers to track location. [24] In 2020, law enforcement used geofence warrants to access the location history of all people within a geographical range of an arson incident during the Black Lives Matter protests. [25] There is both a lack of clarity in the validity of these warrants under constitutional scrutiny, and a lack of constitutionality in the executors’ (as in both telecom providers and law enforcement’s) reasonable good-faith belief that their conduct is lawful. If geofence warrants continue both under a circuit split and operating with ambiguous legality, then it becomes increasingly plausible that law enforcement will have multiple avenues to defend unfair prosecution and ill-begotten evidence. To have both unclear legal boundaries around invasive technology and Chatrie as case precedent would wreak havoc on privacy protections.

As Chief Justice Roberts said in Carpenter, modern cell phones let the government achieve “near perfect surveillance.” [26] A clear ruling on the Supreme Court level in response to Chatrie could answer and clarify when Fourth Amendment protections apply to digital data and when, if ever, geofence warrants are constitutional. Fourth Amendment warrant procedures need to adapt accordingly to these shifts. It’s not just those cell site locations like AT&T that still remain, but also companies like Uber, Apple, and Snapchat, now that Google has stepped aside. Chatrie could uphold the protections of privacy in the spirit of the Fourth Amendment, adapting it to established case law and outlawing geofence warrants in favor of constitutional rights. 

Edited by Ewa Siemiatkowskia and Andrew Chung

[1] “Docket for 25-112: Okello T. Chatrie, Petitioner v. United States,” Supreme Court, 2025, www.supremecourt.gov/docket/docketfiles/html/public/25-112.html.

[2] U.S. Const. amend. XIV.

[3] Deanna Paul, “Alleged Bank Robber Accuses Police of Illegally Using Google Location Data to Catch Him,” Washington Post, November 22, 2019, https://www.washingtonpost.com/technology/2019/11/21/bank-robber-accuses-police-illegally-using-google-location-data-catch-him/. 

[4] United States v. Chatrie, 107 F.4th 319 (4th Cir. 2024). 

[5] Nathaniel Sobel, “Do Geofence Warrants Violate the Fourth Amendment?,” Lawfare, 2020, https://www.lawfaremedia.org/article/do-geofence-warrants-violate-fourth-amendment. 

[6] “Man Indicted for Armed Robbery of Credit Union,” United States Attorney's Office, Eastern District of Virginia, September 18, 2019, https://www.justice.gov/usao-edva/pr/man-indicted-armed-robbery-credit-union.

[7] United States v. Chatrie, 107 F.4th 319 (4th Cir. 2024).

[8] United States v. Chatrie, 107 F.4th 319 (4th Cir. 2024) (en banc)

[9] Carpenter v. United States, 585 U.S. 296, 315 (2018). 

[10] Chatrie, 590 F. Supp. 3d at 907 (E.D. Va. 2022).

[11] Chatrie, 590 F. Supp. 3d at 909. (E.D. Va. 2022).

[12] Chatrie, 590 F. Supp. 3d at 936. (E.D. Va. 2022).

[13] Chatrie, 590 F. Supp. 3d at 936. (E.D. Va. 2022).

[14] Carpenter, 585 U.S. 312 (2018).

[15] Chatrie, 590 F. (E.D. Va. 2022).

[16] Chatrie, 590 F. (E.D. Va. 2022).

[17] Smith, 110 F. (5th Cir. 2024). 

[18] Smith, 110 F. (5th Cir. 2024). 

[19] Sundar Pichai, “Keeping Your Private Information Private,” Google, June 24, 2020, https://blog.google/technology/safety-security/keeping-private-information-private/#:~:text=Web%20%26%20App%20Activity%20auto%2Ddelete,change%20your%20auto%2Ddelete%20option. 

[20] Lars Daniel, “Google to Stop Giving Location Evidence to Law Enforcement.” Forbes, October 8, 2024, https://www.forbes.com/sites/larsdaniel/2024/10/08/google-to-stop-sharing-location-data-with-law-enforcement/; Marlo McGriff, “Updates to Location History and New Controls Coming Soon to Maps,” Google, December 12, 2023, https://blog.google/products/maps/updates-to-location-history-and-new-controls-coming-soon-to-maps/. 

[21] United States Code, title 18, section 3105 (current through Pub. L. No. 118-42, 2024).

[22] Lizzie Epton, “Beyond GPS: Leveraging Cell + WiFi Triangulation for Precise IoT Location Tracking,” Blues, May 7, 2025, https://blues.com/blog/beyond-gps-leveraging-cell-wifi-triangulation-for-precise-iot-location-tracking/. 

[23] Thomas Brewster, “AT&T and T-Mobile Are Giving Cops Geofenced Location Data, Even Though It’s Inaccurate,” Forbes, February 23, 2024, https://www.forbes.com/sites/thomasbrewster/2024/02/23/att-t-mobile-geofence-orders/. 

[24] “ACLU of Florida v. City of Sarasota - Stingray Cell Phone Tracking | American Civil Liberties Union.” American Civil Liberties Union, June 2, 2014, www.aclu.org/cases/aclu-florida-v-city-sarasota-stingray-cell-phone-tracking. Accessed 12 Dec. 2025.

[25] Zack Whittaker, “Minneapolis Police Tapped Google to Identify George Floyd Protesters | TechCrunch,” TechCrunch, February 6, 2021, https://techcrunch.com/2021/02/06/minneapolis-protests-geofence-warrant/.

[26] Carpenter, 585 U.S. 312 (2018).