Google tracks the vast majority of cellphones in the United States, collecting your location, usage and device data through installed software and apps. The tracking occurs by various autonomous processes you cannot see or stop, even when you turn off location history, and Google and other companies keep that data for years. Outside of your control and wherever you go, your cellphone continuously creates a durable and revealing digital trail, and law enforcement agencies can get warrants to obtain it.
But some of those warrants aren’t looking for data about a specific person. Instead, police are compelling tech companies to reveal every cellphone in a particular area during certain time periods. Called geofence warrants, their use is at the heart of a case before the U.S. Supreme Court that will determine what the Fourth Amendment’s protections against unreasonable search and seizure mean in the digital age.
