The U.S. Supreme Court, moving cautiously in an era of rapidly changing technology, ruled on Monday that law enforcement’s warrantless installation and use of a GPS device to track a suspect’s vehicle violated privacy rights protected by the Fourth Amendment.

“It is important to be clear about what occurred in this case: The government physically occupied private property for the purpose of obtaining information,” Justice Antonin Scalia wrote for the unanimous court. “We have no doubt that such a physical intrusion would have been considered a ‘search’ within the meaning of the Fourth Amendment when it was adopted.”