A US circuit court has handed privacy advocates a surprising reversal on a landmark pro-privacy decision: Last year, the court ruled against the government in the case of Quartavious Davis, whose cell phone was tracked by cops as he went on a three-month robbery spree. Privacy advocates celebrated that result as a new anti-snooping legal precedent. But now prosecutors could use the same court's opposite finding to instead justify warrantless snooping on your cellphone's location.

In a decision published Tuesday, a panel of 11th circuit judges overturned the ruling the same circuit court made last year in US vs. Davis, which found that obtaining Davis' past cellphone location without a warrant violated his fourth amendment right to privacy. The new ruling instead finds that because Davis' phone location data wasn't Davis's property, but the property of his phone carrier, MetroPCS—a legal argument known as the "third party doctrine"—he had no expectation of that data's privacy, and the cops tracking him didn't in fact need a warrant.

"It’s a huge setback as compared to the decision it vacated," says Susan Freiwald, a privacy-focused University of San Francisco Law School professor. "These decisions only come out every couple of years. And in that sense it’s very disappointing."

Since 2012, when the Supreme Court ruled in US vs. Jones that police couldn't place a tracking device on a suspect's automobile without a warrant, the privacy community has been waiting for a similar ruling that would apply to phones. Snooping on a modern smartphone's data and phone records, after all, is at least as invasive as any GPS tracking device on a car.

The ruling in Davis' case last year looked like it might finally set that precedent against warrantless phone tracking. "The court’s opinion is a resounding defense of the Fourth Amendment’s continuing vitality in the digital age,” said Nathan Wessler, an attorney with the American Civil Liberties Union told WIRED at the time. Well-known civil liberties attorney Jennifer Granick even wrote in an op-ed for WIRED at the time that the appellate ruling could undermine the NSA's collection of phone metadata, which it has also justified using the third party doctrine.

Instead, the reversal of that ruling comes as a blow to privacy advocates seeking more protections for mobile devices. The same court's review by a larger panel of judges—what's known as an en banc ruling—now reasserts the third party doctrine to insist that Davis had no reasonable expectation of privacy for his cell phone records. "Davis can assert neither ownership nor possession of the third-party’s business records he sought to suppress," the court's decision reads. "Instead, those cell tower records were created by MetroPCS, stored on its own premises, and subject to its control."

The court’s reversal actually leaves the question of warrantless phone tracking in limbo.

Even so, the Davis ruling shouldn't be read as justifying cell phone location tracking so much as delaying the resolution of the question, says University of San Francisco law professor Freiwald. She points out that the court was careful to narrow its ruling. The judges note that Davis used an older cell phone, which allowed only which cell tower he connected to at a given time to be tracked; He wasn't tracked in real time, no location data was associated with his text messages, and the tracking lacked the precision of GPS or Wi-Fi-based location surveillance. "Even in an urban area, MetroPCS’s records do not show, and the examiner cannot pinpoint, the location of the cell user," the ruling reads. "Ironically, Davis was using old technology and not the new technology of a smartphone equipped with a GPS real-time, precise tracking device itself."

That means the panel's ruling about an older type of phone doesn't actually open up modern smartphones to the same sort of location surveillance, Freiwald says. At the same time, she admits that lower courts may misinterpret it to leave smartphone users vulnerable to that sort of more precise tracking. "It’s a decision that looks backward rather than forward...It applies to the kind of monitoring that was going on five years ago," she argues. "In the mean time, all the lower courts are quite likely to read it more broadly than its actual terms, and the government will argue that it covers more than it really does."

In fact, the 11th circuit's reversal on Davis leaves the question of warrantless phone tracking in limbo. Several state courts have ruled that the practice is unconstitutional, including Massachusetts, New Jersey and Florida, while some higher courts now seem to allow it. "It’s a hodgepodge," says Electronic Frontier Foundation civil liberties lawyer Hanni Fakhoury. "What does all this mean for someone who lives in Florida? One court has said yes and one has said no. That's problematic."

Fakhoury says he still has hope that the Supreme Court might take up the case or a similar one. And if it did, its recent privacy rulings like Jones and US vs. Riley—which found that the contents of a phone couldn't be searched without a warrant at the time of the owner's arrest—indicate that it could finally declare the practice of warrantless cell phone tracking unconstitutional. "If the signals they’ve given in Jones and Riley are any indication, they could very well say there are privacy issues here," says Fakhoury. "I’m optimistic that the Supreme Court would get his right."

Here's the full ruling:

Davis Reversal