Geofence warrants now fall within Fourth Amendment scrutiny when law enforcement obtains historical cellphone location data from a technology provider. The U.S. Supreme Court’s decision in Chatrie v. United States establishes that even a short period of location history can constitute a search. For investigators, the ruling shifts attention to whether geofence warrants satisfy probable cause and particularity requirements while minimizing the collection of uninvolved people’s data.
Chatrie v. United States, 146 S. Ct. 2193 (2026)
Officers investigating a credit union robbery in Midlothian, Virginia, knew where and when the crime occurred, and surveillance video showed the robber apparently talking on a cellphone near the bank before the robbery. What they did not know was who he was. So, they asked Google which mobile phones had been near the crime scene.
That “reverse” approach is the essence of a geofence warrant. Investigators identify a geographic area and time period and obtain a warrant requesting location information from Google for devices that were present within the designated area. The technique can be useful when police have a crime but no suspect. It also creates an obvious Fourth Amendment problem, since the initial search may necessarily collect information associated with people for whom police have no individualized suspicion.
In Chatrie v. United States, the U.S. Supreme Court confronted that problem for the first time. The robbery occurred on May 20, 2019. Several weeks later, investigators obtained a warrant directing Google to search its location history database for devices located within a 150-meter radius of the credit union during approximately an hour surrounding the robbery.
The warrant contemplated a three-step process:
- Google would identify devices within the geofence and time frame and provide anonymized location information.
- Investigators could then narrow the group and obtain additional location information for selected devices.
- Finally, after further narrowing, Google would disclose identifying information associated with the remaining accounts.
The process ultimately led investigators to Okello Chatrie, whose phone entered the geofence area roughly 10 minutes before the robbery and then left the bank and traveled toward a residential neighborhood.
Chatrie moved to suppress the evidence, arguing the geofence process violated the Fourth Amendment. The district court concluded the warrant violated the Fourth Amendment but denied suppression under the good-faith exception. The 4th Circuit ultimately ruled against Chatrie on a different ground, concluding he lacked a reasonable expectation of privacy in the location information Google possessed.
“When police obtain a person’s historical cellphone location information from a technology company, they have conducted a Fourth Amendment search.”
The Supreme Court disagreed. Writing for the Court, Justice Kagan held that law enforcement conducts a Fourth Amendment search when it obtains this kind of historical cellphone location information from a third-party provider.
The decision builds on Carpenter v. United States, the 2018 case that held acquisition of historical cell-site location information can constitute a search. But Chatrie resolves two important questions left open after Carpenter.
First, it doesn’t matter that Google rather than a cellular carrier collected the location information. The traditional third-party doctrine generally provides that a person loses Fourth Amendment protection in information voluntarily conveyed to another. But the Court declined to apply that rule mechanically to the enormous quantity of location information generated by modern smartphones and their applications.
Second, there is no short-duration exception. Carpenter involved at least seven days of location information. That led to considerable debate over whether obtaining location information for a much shorter period fell outside Carpenter. Chatrie involved only about two hours of Chatrie’s location history – but that did not matter to the Court.
The Fourth Amendment protection recognized by the Court does not suddenly disappear because investigators request hours rather than days of historical location information. Modern smartphones can create extraordinarily revealing records of a person’s movements, and the Court rejected a rule under which the government would receive a warrantless window merely because its inquiry was relatively brief.
For investigators, however, it is equally important to understand what the Supreme Court did not hold. The Court did not hold geofence warrants are categorically unconstitutional. It did not decide whether the warrant obtained by investigators in Chatrie’s case was supported by sufficient probable cause. And it did not finally decide whether the three-stage process satisfied the Fourth Amendment’s particularity requirement.
Instead, the Court resolved the threshold issue: Obtaining Chatrie’s location history was a search. It sent the case back to the court of appeals for consideration of the remaining Fourth Amendment issues.
After Chatrie, the question is no longer whether police can avoid Fourth Amendment scrutiny because the location information is maintained by a third-party technology company or because investigators seek only a short period of data. They can’t. Obtaining the information is a search.
The harder question becomes whether a particular geofence warrant satisfies the ordinary requirements of the Fourth Amendment. Geofence investigations effectively work backward from traditional search warrants. Ordinarily, officers establish probable cause regarding an identified person, place, device, or account and obtain authority to search it. With a geofence warrant, investigators may begin without knowing whose information they are seeking. The search itself helps identify the suspect. That does not necessarily make the technique unconstitutional, but it places considerable importance on how the warrant is constructed.
Investigators and prosecutors should expect courts to examine the following factors:
- The geographic boundaries of the geofence
- The time period involved
- The factual basis for believing the perpetrator carried a device that would generate the requested information
- The number of uninvolved persons likely to be swept into the initial search
- The procedures used to anonymize and narrow the data
- The evidence required for investigators to justify obtaining identifying information
Justice Jackson, joined by Justice Sotomayor, agreed that obtaining Chatrie’s location history constituted a search but concluded at least portions of the three-stage process failed the Fourth Amendment’s probable cause and particularity requirements. Justice Gorsuch agreed with the Court’s judgment but reached the Fourth Amendment issue through a different analytical route.
Justice Alito dissented, joined in various portions by Justices Thomas and Barrett. The dissent criticized the majority for expanding Carpenter and weakening traditional third-party doctrine.
For law enforcement, the operational lesson from Chatrie is straightforward but important. Geofence technology remains a potentially valuable investigative tool, particularly in serious cases where officers know when and where a crime occurred but do not know the suspect’s identity. But investigators should no longer think of location information held by a technology provider as ordinary third-party business records that may fall outside Fourth Amendment protection.
The warrant application must do the constitutional work. Investigators should explain why location data is likely to identify the offender or other relevant persons, justify the geographic area and time period as narrowly as the investigation permits, describe how irrelevant devices will be eliminated, and establish meaningful limits on when anonymized information may be converted into identifying information.
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Perhaps most importantly, Chatrie should not be seen as a prohibition on geofence warrants. What the Court said is both narrower and more consequential: When police obtain a person’s historical cellphone location information from a technology company, they have conducted a Fourth Amendment search. The next generation of geofence cases, if there is one, will determine what a constitutionally adequate warrant for that search looks like.
I say “if there is one” because of a recent development that may make much of this debate less consequential going forward. Google has changed how it stores the location history that once made these warrants possible. Most user location data is now stored directly on individual devices rather than on Google servers. Optional cloud backups are now encrypted so Google cannot access them. Because of this, the tech giant generally no longer possesses (or possesses but can’t read) the location-history data it could once search in response to a geofence warrant. Therefore, while Chatrie may establish an important Fourth Amendment rule, the practical usefulness of geofence warrants (of the type seen in Chatrie) is already fading.
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