Police departments around the U.S. must now obtain a warrant based on probable cause before they can secretly attach a GPS device to your car, the Third Circuit Court of Appeals ruled Tuesday.

The case, U.S. v. Katzin, which was brought by the ACLU is being hailed as a victory in the fight against government surveillance.

Last year the Supreme Court unanimously ruled in U.S. v. Jones that attaching a GPS device to a citizen's vehicle constitutes a “search” under the Fourth Amendment. However, due to unclear wording in the case's ruling, police departments around the country have, until now, evaded having to attain warrants to do so.

"GPS devices have become a favored tool of law enforcement, and their highly intrusive nature cries out for clear judicial regulation," read the amicus brief filed by the ACLU, the ACLU of Pennsylvania, Electronic Frontier Foundation, and the National Association of Criminal Defense Lawyers.

"Today's decision is a victory for all Americans because it ensures that the police cannot use powerful tracking technology without court supervision and a good reason to believe it will turn up evidence of wrongdoing," said ACLU Staff Attorney Catherine Crump, who argued before the three-judge panel. "These protections are important because where people go reveals a great deal about them, from who their friends and business associates are to what doctors they go to."

_____________________