Supreme Court says location history is protected by the Fourth Amendment

The Supreme Court ruled Monday that cellphone location history is protected by the Fourth Amendment, sharply limiting the government’s use of geofence warrants. In a 6-3 decision, the Court said police need a warrant and must show reasonable cause before turning location services into a tool for government tracking.

Justice Elena Kagan, writing for the majority, said there was no reason to treat location history held by companies such as Google differently from other cellphone tracking data the Court has already protected. Kagan wrote that police conduct a Fourth Amendment search when they demand records showing where a person’s phone has been, even if the request covers a short period and the data is held by a third party.

The case arose from an armed bank robbery investigation involving Okello Chatrie. According to the Court, police used a geofence warrant to ask Google for information about phones in the area, then used a multi-step process to narrow the list before arresting Chatrie, who had chosen settings that shared his location with Google every few minutes.

Chatrie was sentenced to 12 years in prison, according to the Court record, and challenged the warrant as an unconstitutional search. The federal government argued that no Fourth Amendment search occurred because investigators obtained only a limited slice of his location data, and because Chatrie had voluntarily shared information with Google while moving in public.

Kagan rejected those arguments for the majority. She said modern cellphone users often enable location services so apps will function, and that agreeing to such services does not mean people surrender privacy rights against government access.

The majority also cited Justice Sonia Sotomayor’s view that even short-term location monitoring can expose sensitive details about a person’s family, politics, work, religion and intimate life. Visits to places such as medical clinics, lawyers’ offices or strip clubs can reveal information far beyond a person’s physical route, the Court said.

Dissent warns of legal disruption

Justice Samuel Alito dissented, saying the majority had unsettled established Fourth Amendment doctrine. Alito argued that courts should assess location data requests more narrowly, including by looking at the specific app or service involved, rather than applying a broad rule to cellphone location information held by third parties.

Alito wrote that the decision could require police to obtain warrants for any third-party cellphone location request, even when the period is brief or the user voluntarily disclosed the information. In a footnote, he questioned how courts would treat location data generated by services such as Apple Pay.

Kagan said the dissent and the government misunderstood how people use smartphones. The majority said ordinary use of phone apps should not be treated as a decision to make private location information freely available to law enforcement.

Alito also said the Court should not have taken the case because, in his view, the ruling may not change Chatrie’s outcome if lower courts find the search reasonable. The majority disagreed and sent the case back for lower courts to decide whether the search was reasonable under the Fourth Amendment standard the Court announced.

Privacy groups and tech industry back ruling

Andrew Crocker, surveillance litigation director at the Electronic Frontier Foundation, said the group welcomed the decision even though the Court did not declare geofence warrants unconstitutional in every case. Crocker said the ruling confirms that people have a privacy interest in location data showing their movements in the physical world.

Matt Schruers, chief executive of the Computer & Communications Industry Association, which includes Google and Apple among its members, also praised the ruling. Schruers said the decision recognizes that Fourth Amendment protections apply to geolocation information regardless of the technology involved.

This story draws on original reporting from Ars Technica.