AT&T has entered the legal fracas over whether court warrants are required for the government to obtain their customers' cell-site location history.

The telecom, while not siding one way or the other, said Monday the courts should adopt a uniform policy nationwide. As it now stands, there's conflicting appellate rulings on the matter. The Supreme Court has yet to decide the issue.

The Dallas, Texas-based company told [PDF] the following to the 11th US Circuit Court of Appeals, which is considering the issue:

The government orders at issue—and tens of thousands like them annually—seek detailed records that can reveal the location and movements of the user of a particular mobile device, often over a relatively lengthy period. In many cases, the government can use that information to track the ongoing movements of particular targeted individuals, building a detailed understanding of the target’s patterns of behavior and social and professional contacts and activities. Network, application, and other technological developments are making that location information ever more detailed and precise. Considerable legal uncertainty surrounds the standards the government must satisfy to compel the production of location information, and achieving legal clarity is essential to protecting consumer privacy, defining the scope of legitimate law enforcement interests, and ensuring the efficient operation of companies operating in various sectors of the digital economy.

The case before the appeals court involves a Florida man, Quartavious Davis. He was sentenced to life for a string of robberies. His 2012 conviction rested largely on mobile phone records pegging his location near six of seven heists. The Atlanta-based appeals court, ruling in Davis' case in June, concluded that warrants were required.

But President Barack Obama's administration urged the court to rehear the case: [PDF]

On the merits, it is not persuasive to hold that cell site data is always within the subscriber's reasonable expectation of privacy—no matter whether the information in question pertains to a single phone call spanning a few seconds or thousands of phone calls spanning a few years, no matter whether the subscriber makes a call in plain view in a public place or from the privacy of his own home, and no matter how explicit the warning incorporated into the customer’s service contract.

The government also noted that the court's decision conflicted with other appellate decisions. The appeals court decided to rehear the case at a yet-to-be-determined time.

Davis successfully argued that the public maintains a reasonable expectation of privacy that their public movements won't be catalogued for the government unless a probable cause warrant is issued by a judge. The authorities did not get a warrant in Davis' prosecution.

"Thus, the exposure of the cell site location information can convert what would otherwise be a private event into a public one. When one’s whereabouts are not public, then one may have a reasonable expectation of privacy in those whereabouts," the court ruled. (Because the court decided to rehear the case, the decision is no longer case law.)

At least three other federal circuits, there are 13 altogether, have ruled differently from the 11th Circuit. In all of the cases, the authorities argued that so-called cell-site records are not constitutionally protected and are business records that telcos may hand over if the government asserts there are reasonable grounds to believe the data is relevant to an investigation.

The stakes are high. The government is embracing warrantless cell-site tracking as a surveillance tool in the aftermath of a Supreme Court ruling in 2012 that said the authorities needed a warrant to affix GPS trackers to vehicles. In that case, the justices ruled that the actual installation of a GPS device on a vehicle was the equivalent of a search usually requiring a warrant. Mobile phones, usually in a suspect's pocket or purse, don't require any government installation.

The American Civil Liberties Union and the Center for Democracy & Technology also weighed in to the case with a filing Friday. They said a massive amount of information was at stake:

As of December 2013, there were 335.65 million wireless subscriber accounts in the United States, responsible for 2.61 trillion annual minutes of calls and 1.91 trillion annual text messages. Cell phone use has become ubiquitous: more than 90 percent of American adults own cell phones and more than a third of US households have only wireless telephones.

The National Association of Criminal Defense lawyers also took the ACLU's and CDT's side, filing its own brief [PDF] Friday.