Supreme Court reviews constitutionality of geofence warrants

On April 27, the Supreme Court heard oral argument in Chatrie v. U.S., a case considering the constitutionality of geofence warrants. As I explained in an earlier post, geofence warrants require a company to turn over information regarding the devices that it tracked within a targeted area over a time period of interest. The question before the court is whether the geofence warrant in Chatrie violated the Fourth Amendment, which protects against “unreasonable searches and seizures.”

The Chatrie case

After being charged in relation to a 2019 credit union robbery based in part on evidence obtained through a geofence warrant, Okello Chatrie challenged its constitutionality. In March 2022, a federal district court judge declined to suppress the evidence from the warrant, citing the “good faith” exception.

In July 2024, a three-judge panel of the 4th U.S. Circuit Court of Appeals affirmed but gave a different reason: Chatrie, the panel concluded, “did not have a reasonable expectation of privacy” in his location data. Chatrie then sought and received an en-banc rehearing from the full 4th Circuit, which in April 2025 affirmed the district court’s opinion. Chatrie submitted a petition to the Supreme Court. In January 2026, the court granted the petition.

A different kind of Fourth Amendment case

Historically, most Fourth Amendment cases have involved questions of whether a particular type of warrantless search violates the Fourth Amendment. For instance, in the 2018 case Carpenter v. U.S., the court ruled that it was unconstitutional for law enforcement to acquire, without a warrant, data regarding which cell towers a suspect’s phone was connected to. In the classic 1967 decision Katz v. U.S., the court found that the government had violated the Fourth Amendment when it attached a listening device to a public phone booth without a warrant.

By contrast, in Chatrie there was a warrant. The question therefore is whether the warrant itself was unconstitutional. The 4th Circuit en-banc panel’s majority opinion did not provide a substantive analysis of this question, consisting only of a single sentence affirming the district court. There were also over 100 pages of concurrences, but those concurrences aren’t the majority opinion of the panel. Notably, in a different geofence warrant case relating to a Mississippi robbery, a three-judge panel of the 5th Circuit unanimously concluded in 2024 that geofence warrants “are modern-day general warrants and are unconstitutional under the Fourth Amendment.” 

The challenges with physical world analogies

In the Chatrie Supreme Court argument, the justices explored analogies between geofence warrants and searches of real-world physical spaces. For example, if investigators suspect that one of the customers of a storage facility is unlawfully storing a gun, what would be the Fourth Amendment considerations involved in doing an initial, high-level search by looking at all of the storage lockers to identify a subset of lockers to then search more extensively?

But analogies like these don’t map cleanly onto what occurs in geofence searches. On one hand, a geofence search involves an automated examination of location records for millions of devices—a magnitude that has no meaningful physical world counterpart. On the other hand, a geofence search is also extremely targeted, aimed at identifying devices that were active in a very short window of time and space. These sorts of divergences limit the utility of comparing digital searches to searches of physical spaces.

The likelihood of a narrow ruling

While Chatrie v. U.S. is about one specific geofence warrant, the justices’ questions telegraphed a recognition that the court’s decision will have wider implications for geofence warrants generally, and likely by extension, for some other types of digital searches. The court seems unlikely to issue a ruling that will be read as a categorical rejection of the constitutionality of geofence warrants and equally unlikely to issue a ruling indicating that they are presumptively constitutional.

Instead, many of the questions turned on the specifics of how the geofence search in Chatrie was conducted. Pursuant to the warrant, investigators used a three-step process. At step one, Google provided (theoretically) anonymized location information for devices within the geofence for a one-hour period starting 30 minutes before the robbery. This step yielded 19 accounts (with each account likely corresponding to a single device). At step two, investigators selected nine of those accounts and asked Google to provide location information for a two-hour period centered on the robbery and unconstrained by the geofence. At step three, investigators asked Google for subscriber information for three of those accounts, leading them to Chatrie.

But this three-step process was laid out in advance in a single warrant. At the time the court issued the warrant, no one knew how many devices would be identified by the search. Once the warrant was issued, it was left to law enforcement and Google to work out the details of what criteria to use in narrowing the search between each of the three steps. The lack of court oversight in the narrowing process opens the door to searches that fail to meet the Fourth Amendment’s probable cause and particularity requirements—putting at risk the constitutional rights of anyone identified through the search.

Contours of a possible ruling?

In one of the most telling exchanges of the argument, Justice Sonia Sotomayor said that “There are … many jurisdictions in which the government is going back at step 2 and step 3, correct? That’s not much of a burden. … If you have gotten step one and you can explain your reasons for why you’re narrowing the warrant and—and why you need it at step 2, you could do that.” Deputy Solicitor General Eric Feigin, representing the United States, responded, “we could do that and with more recent warrants, the government has done that.”

The government thus acknowledged not only that more comprehensive court supervision through the latter stages of a multistep geofence search was possible, but that it was already occurring. This removes any potential argument that a geofence warrant framework requiring increased oversight to ensure Fourth Amendment compliance would be so overly burdensome as to frustrate investigations.

Furthermore, earlier in the argument, Adam Unikowsky, arguing on behalf of Chatrie, had highlighted the same issue, pointing out that “the warrant itself doesn’t provide any criteria” for narrowing the search. Justice Ketanji Brown Jackson responded by asking, “If it did, would it be more particularized? … ” Unikowsky recognized that a ruling finding the warrant flawed with respect to steps two and three “would be a very narrow resolution of this case,” adding that “that alone is a sufficient basis to invalidate this warrant even if the Court disagrees with our broader arguments.”

Taken together, these exchanges suggest a potential outcome where the court finds the warrant in Chatrie unconstitutional because it lacked probable cause or particularity for the approaches used in refining the search in steps two and three. This would provide a narrow win for privacy advocates, while not blocking the government from using geofence warrants that, unlike the warrant in Chatrie, include greater court oversight across multiple steps regarding the specific criteria used to hone in on devices of interest.

Another chapter in the court’s Fourth Amendment jurisprudence

However the court ends up ruling in Chatrie, it will become the latest in a string of important rulings on how the Fourth Amendment applies to digital technologies. As noted above, the court seems very unlikely to find geofence warrants categorically unconstitutional. Thus, if the court finds the Chatrie warrant insufficient, hopefully it will also provide some guidance. Prosecutors, law enforcement investigators, and lower courts will need to know the bounds of what is and is not permissible when seeking to obtain a geofence warrant that satisfies the Fourth Amendment.