WASHINGTON, DC – Following today’s decision at the Supreme Court in Chatrie v. United States, a case in which the Court considered whether “geofence warrants” violate the Fourth Amendment, Constitutional Accountability Center Deputy Chief Counsel Brian Frazelle issued the following reaction:

By using “geofence” technology, police can retrace the movements of every person who carried their cell phone within a designated space during a designated time period. This technique may be useful in solving crimes, but it also sweeps in the movements of countless innocent people, revealing private details about where they travelled and when, even inside their own homes. Today’s Supreme Court decision correctly holds that when police use this new technology, they are conducting a “search” that must be reasonable under the Fourth Amendment.

This decision is an important step toward retaining our constitutionally guaranteed privacy and security in the digital age. First, the decision strongly reaffirms the Fourth Amendment’s role in safeguarding privacy—not just property—from unreasonable government intrusions. Even though the police obtain cell-phone GPS records from private companies like Google, rather than by directly invading a person’s phone, the Court held that acquiring these records is governed by the Fourth Amendment’s limits. Second, as our amicus brief advocated, the Court established a bright-line rule that obtaining cell phone location information is regulated by the Fourth Amendment no matter how long the surveillance lasts or what kind of app created the GPS information. This gives both the police and the public the clarity they need.

By recognizing that the Fourth Amendment places limits on law enforcement’s access to cell phone location information, no matter how much data is involved, the Court properly continued its recent trend of ensuring that advances in surveillance technology don’t erode the privacy against government intrusion that the Fourth Amendment guarantees the American people.