Blue Brief 2025-2026

outside of the geofence and over a longer, two hour period. Third, police would narrow the list further by comparing the additional information against other known information specific to the crime, at which point Google would finally turn over identifying information for those particular users. The structure of that process for establishing cause is at least roughly analogous to the physical search at issue in Ybarra v. Illinois , where the Court held that a warrant to search a bar and its employees did not create blanket authority to conduct even pat-down searches of the bar’s patrons. In situations like Ybarra , if an initial search yields additional evidence that creates independent probable cause to search the patrons, the police can then obtain additional warrants to do so. In geofence cases like Chatrie , the government will want to argue that the data reviewed at step one of the warrant process does not violate a user’s privacy at all as it is anonymized, and that by step three probable cause exists to learn the identifying information of the users whose locations fit the other evidence of the crime. (In a concurrence in Chatrie, Justice Jackson wrote separately to argue that the geofence warrant was invalid because it did not require an independent magistrate to evaluate whether cause existed

to winnow the list but relied instead on the officers’ “attempts” to do so.)

As Justice Alito notes in dissent, however, regardless of the Fourth Circuit’s eventual disposition of the reasonableness question, Chatrie himself is unlikely to obtain relief. This is due to the so-called “good faith” exception, which bars the exclusionary remedy for Fourth Amendment violations in cases involving a facially valid warrant unless the defendant can show that the police acted in bad faith in obtaining it. Moving forward, the most clear-cut impact of Chatrie will be its extension of Carpenter to much shorter searches, an issue explicitly left open by Carpenter itself. Furthermore, the 6-3 holding appears broadly to continue on the course set by that case, which recognized the intimacy of the data captured by our devices and the effective involuntariness of both their presence on our persons and the subtle activation of location tracking features within them. It will be necessary for courts to provide further guidance for law enforcement on reasonableness requirements for geofence warrants and other digital forms of searching, in order to balance these new privacy interests against the competing state interests in solving crimes.

Erin Sheley

The Law School is grateful to the law librarians at USD’s Pardee Legal Research Center, and in particular to Elizabeth Parker and Sasha Nuñez, for their hard work on these essays.

UNIVERSITY OF SAN DIEGO SCHOOL OF LAW | Faculty Review of 2025-2026 U.S. Supreme Court Term | Page 37