In what was described as an unprecedented victory for cell phone privacy, the Electronic Frontier Foundation reported on Thursday that cell phone location information has been found by a federal court to be protected by the 4th Amendment. A warrant based on probable cause must be issued before the government can seize such records.

The DOJ had previously asked a federal court to allow them to access location information stored by a mobile phone provider without a warrant. The Electronic Frontier foundation (EFF), in a friend-of-the-court brief, opposed the government’s appeal.

"Cell phone providers store an increasing amount of sensitive data about where you are and when, based on which cell towers your phone uses when making a call. Until now, the government has routinely seized these records without search warrants," said EFF Senior Staff Attorney Kevin Bankston.

"This landmark ruling is hopefully only the first of many. Just as magistrates across the country have begun denying government requests to track cell phones in real-time without warrants, based on arguments first made by EFF, so too do we hope this decision will spark new scrutiny of the government’s unconstitutional seizure of stored cell phone location records."

The case was heard before the federal court in the Western District of Pennsylvania. The American Civil Liberties Union (ACLU), the ACLU Foundation of Pennsylvania and the Center for Democracy and Technology (CDT) joined in presenting the EFF brief.

The Fourth Amendment to the U.S. Constitution says, "The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."