WASHINGTON (Gray DC) - The Supreme Court on Monday handed down a significant Fourth Amendment ruling that strengthens constitutional protections for Americans’ cellphone location data.

In a 6-3 decision, the justices determined that when police obtain a person’s stored location history from a company such as Google, they are conducting a search under the Fourth Amendment. That means law enforcement must satisfy the Constitution’s protections against unreasonable searches before accessing that information.

The case, Chatrie v. United States, arose from the investigation into a 2019 armed robbery at a credit union in Virginia.

After traditional investigative leads stalled, police obtained a “geofence warrant” directing Google to provide location history for every device detected within a defined area around the crime scene during a specific period. Investigators then narrowed the list until they identified Okello Chatrie, who was later convicted.

On Monday, the court sided with the defendant. Writing for the majority, Justice Elena Kagan said people retain a reasonable expectation of privacy in their cellphone location history, even when that information is stored by a third-party technology company.

“An individual has a reasonable expectation of privacy in records about his cell phone’s location,” Kagan wrote, rejecting the government’s argument that users surrender those protections simply by enabling location services.

Justice, however, stopped short of deciding whether the geofence warrant used in Chatrie’s case satisfied the Fourth Amendment. Instead, the justices sent the case back to a lower court to determine whether the warrant was supported by probable cause and sufficiently narrow in scope.

The ruling is viewed as one of the Court’s most significant digital privacy decisions since its 2018 decision requiring warrants for most historical cellphone location records.

Privacy advocates argued geofence warrants can sweep up information from hundreds or even thousands of innocent people who happen to be near a crime scene, while law enforcement has maintained the tool is valuable for solving crimes when investigators have few leads.

The decision does not prohibit geofence warrants altogether. Instead, it establishes that requests for large amounts of location data are subject to Fourth Amendment protections, meaning future warrants will likely face greater judicial scrutiny before police can obtain them.