Supreme Court says police need a warrant for detailed cellphone location data in privacy win
Court expands Fourth Amendment protections for digital location records
The U.S. Supreme Court has ruled that law enforcement needs a warrant to access detailed cellphone location data, marking a major victory for digital privacy and tightening limits on a controversial form of dragnet surveillance known as geofence warrants.
In Chatrie v. United States, the Court said people have a reasonable expectation of privacy in location data that reveals their movements in the physical world, and that even short-term tracking of those movements can amount to a search under the Fourth Amendment. The ruling builds on the Court’s 2018 decision in Carpenter v. United States, which addressed prolonged tracking through cell phone location records.
The new decision goes further by recognizing that brief surveillance can still expose “private matters,” including “a wealth of detail about a person’s familial, political, professional, religious, and sexual associations.” The Court also said records generated by apps on a user’s phone are the user’s “own” and therefore deserve Fourth Amendment protection, even when those records are shared with third-party tech companies.
Geofence warrants have been a flashpoint in privacy debates because they do not identify a suspect or target a specific device. Instead, they require companies—most often Google—to hand over location information for every device in a defined area during a specified time window. Privacy advocates have argued that the practice can sweep up innocent bystanders and expose sensitive travel history.
In Chatrie, police used a 2019 geofence warrant to search for devices near a Northern Virginia crime scene. The area covered several football fields and included homes, businesses and a church. Google was compelled to search accounts belonging to hundreds of millions of users to determine whether any device had been inside the radius.
A federal district court in Virginia had already found in 2022 that the warrant violated the Fourth Amendment, saying that if police want information on every device in an area, they must establish probable cause to search every person there. Today’s Supreme Court ruling makes that logic national law, and could have broad implications for app-generated data well beyond location tracking.
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