In a new 2-1 decision published (PDF) Tuesday, the Fifth Circuit Court of Appeals has held that law enforcement does not need a warrant to obtain cell-site location information (CSLI) from a mobile phone, falling in line with other recent high-level federal court decisions.

In July, however, the New Jersey Supreme Court ruled unanimously that cops do not have this right (at least in the Garden State), setting up a situation where the Supreme Court could rule to settle the debate once and for all.

The Fifth Circuit’s majority judges cited the Stored Communications Act (also known as a 2703(d) order) as grounds to allow CSLI to law enforcement. Under that federal statute, authorities can’t retrieve the contents of electronic communication, but they can find out where and to whom electronic communication was sent. In contemporary cases within the last decade, law enforcement and judges have increasingly used this reasoning to obtain extensive location data that can effectively turn the phone into a tracking device. Such information previously would have required a much higher legal threshold like a probable cause-driven warrant.

In the majority decision, the judges wrote (PDF) that cell site information was nothing more than a business record, which "the Government has neither 'required [n]or persuaded' providers to keep."

"In the case of such historical cell site information, the Government merely comes in after the fact and asks a provider to turn over records the provider has already created," the judges continued. "Moreover, these are the providers’ own records of transactions to which it is a party. The caller is not conveying location information to anyone other than his service provider. He is sending information so that the provider can perform the service for which he pays it: to connect his call."

Not surprisingly, civil libertarians decried the Fifth Circuit's decision. As the American Civil Liberties Union's Catherine Crump wrote:

This ruling is troubling because, as we and the Electronic Frontier Foundation (EFF) argued, only a warrant standard fully protects Americans' privacy interests in their locations and movements over time. Cell phone companies store records on where each of us have been, often stretching back for years. That location information is sensitive and can reveal a great deal—what doctors people visit, where they spend the night, who their friends are, and where they worship. Given the sensitivity of these facts, law enforcement agents should have to demonstrate to a judge that they have a good reason to believe that they will turn up evidence of wrongdoing before gaining access to information that can paint a detailed picture of where a person has been over time.

Still, the Fifth Circuit judges did have one more remedy for mobile phone users who want to keep their location private: just, y'know, "demand" it from your mobile carrier. As they wrote: