Associate Justice Antonin Scalia said that the government’s installation of a GPS device, and its use to monitor the vehicle’s movements, constitutes a search, meaning that a warrant is required.

“By attaching the device to the Jeep” that Jones was using, “officers encroached on a protected area,” Scalia wrote.

CBS News legal analyst Andrew Cohen said today’s decision was a victory for civil libertarians and a defeat for law enforcement officials who had argued that putting a GPS device on a car wasn’t exactly a search under the Fourth Amendment.

via High court: Warrant needed for GPS tracking – CBS News.

Glad to see this one went unanimous and in the freedom direction.  Had this failed, there would be no reason why cops couldn’t tag *anyone* for *any reason* with a GPS-tracker.   That’s not a good society in which to live, and it looks like we’ve avoided becoming that society.  For the time being.