The Supreme Court ruled Monday that police must obtain a warrant before attaching a GPS tracker to a suspect's vehicle, voting unanimously in one of the first major cases to test constitutional privacy rights in the digital age.
The government argued that attaching the tiny device to a car's undercarriage was too trivial a violation of property rights to matter, and that no one who drove in public streets could expect his movements to go unmonitored. Thus, the technique was "reasonable," meaning that police were free to employ it for any reason without first justifying it to a magistrate, the government said.
The justices seemed troubled by that position at arguments in November, where the government acknowledged it would also allow attaching such trackers to the justices' own cars without obtaining a warrant.
The court split 5-4 over the reasoning behind Monday's decision, with Justice Antonin Scalia writing for the majority that as conceived in the 18th century, the Fourth Amendment's protection of "persons, houses, papers, and effects, against unreasonable searches and seizures" would extend to private property such as an automobile...