Chatrie v. United States: A privacy victory before the Supreme Court

On 29 June, the U.S. Supreme Court handed down a 6-3 decision in Chatrie v. United States, ruling that a law enforcement geofence constitutes a search under the Fourth Amendment. 

Justice Elena Kagan, writing for the majority, held that individuals retain a reasonable expectation of privacy in their location history even when held by a third party, in this case Google. The court meaningfully limited the third-party doctrine by rejecting the government's argument that because the data at issue was handed over to a third party, it retained no Fourth Amendment protections. 

However, the court left the specific evaluation of whether the search was reasonable — including whether particularity and probable cause requirements were met at each step of the warrant's multistep process — to the lower court.

Background of the case

On 20 May 2019, an armed robber entered a credit union in Midlothian, Virginia. Security footage captured the suspect walking past a nearby church shortly beforehand, appearing to speak on a cellphone. Police turned to an aggressive digital surveillance technique known as a geofence warrant, transforming a local robbery into a constitutional battleground over the limits of digital privacy.

A geofence warrant reverses traditional policing. Instead of establishing probable cause against a specific suspect and searching their property, law enforcement identifies a physical location and a timeframe, demanding that a company like Google search its user data repositories to figure out everyone who might have been within that area during that window. 

In this case, investigators secured a warrant forcing Google to query its centralized Sensorvault database, a repository containing the detailed location histories of hundreds of millions of active user accounts worldwide that were opted into location history, a Google Maps feature through which locations are compiled into a user-facing timeline.