The Supreme Court has ruled that the government must obtain a warrant before using geofencing technology, essentially slamming the door on a controversial method of tracking suspects.

In a 6-3 decision, the justices concluded that geofence warrants require a search warrant because they involve gathering location data from third-party providers, such as Google. This ruling means law enforcement will need to prove reasonable cause before accessing this data.

The case centered on Okello Chatrie, who was arrested after police used geofence warrants to narrow down suspects in a bank robbery. Chatrie had shared his location with Google every few minutes, allowing the police to track him but leaving him fighting an uphill battle against the Fourth Amendment’s protections.

Justice Elena Kagan’s majority opinion highlighted that people often consent to sharing their location data for convenience, unaware of its wider implications. She wrote: ‘Google repeatedly prompts users to turn on the service, often warning that devices will not “work correctly” otherwise, while not disclosing in that prompt how frequently users’ location information would be recorded, how precise it would be, or how it might be given to the government.’

While Chatrie’s case was a reminder of privacy violations, his sentence of 12 years underlines how these technologies can still have severe real-world consequences for individuals.