The Washington PostDemocracy Dies in Darkness

Your location history is like a fingerprint. And cops can get it without a warrant.

Sen.  Ron Wyden (D-ore.) (Harry Hamburg/AP)

Does it violate your privacy rights for the government to track the minute-by-minute movements of your cellphone? On Tuesday, a federal appeals court said no. And that's a bigger deal than you might think.

The U.S Court of Appeals for the Fifth Circuit held that individuals have no reasonable expectation of privacy over the location data collected by cellphone companies. Civil liberties groups had argued that information about your location was protected by the Fourth Amendment. But the court ruled that information about which cellphone towers your phone has been talking to — which can give a fairly precise idea of its location — is a mere "business record.”

And under a controversial 1979 Supreme Court decision, users don't have Fourth Amendment rights in such records after they "voluntarily" turn the information over to a third party such as a phone company.

Information about where your phone has been might seem innocuous, but it can be surprisingly revealing. Location data can identify where someone sleeps, where they work, who they get a beer with, what medical professionals they visit and what political or religious gatherings they attend. And it’s almost impossible to anonymize this data because, as Jeff Jonas, IBM fellow and chief scientist of the IBM Entity Analytics Group has argued, people are “living in habitrails,” following a standardized schedule in which work and home markers are easy to discern.

In fact, Jonas points out that because no one is exactly where you are at exactly the same time, your location records qualify as a behavioral biometric marker, as distinctive as a fingerprint.

It's not clear whether the Supreme Court will endorse the Fifth Circuit's reasoning. Last year, the high court ruled that GPS surveillance constituted a search in U.S. v. Jones, but based their ruling on the fact that law enforcement had committed a trespass by placing a GPS unit on the defendant’s car. The ruling didn't address the larger question of whether location data itself is protected by the Fourth Amendment.

The New Jersey Supreme Court reached a different verdict on the same type of cell site location data issue earlier this month, but it based its reasoning on New Jersey's constitution, which offers more explicit protections for privacy.

It would be helpful to have a similar level of clarity at the federal level.

Immediately after the leak of an NSA order to Verizon that included a request for "comprehensive communications routing information," the observers speculated that geolocation data fell under the scope of metadata authorized for collection.

But government officials have denied that location data is being collected, although they insist that they have authority to do so. Some reports suggest that officials believe it would be too costly to store. Deputy Attorney General James Cole told the House Intelligence committee: "We don't get any cell site or location information as to where any of these phones were located."

Similarly, NSA Director General Keith B. Alexander told the House Judiciary Committee that the NSA wasn't collecting geolocation metadata "under this program."

However, Sen. Ron Wyden (D-Ore.), who has been an outspoken and crafty critic of the secrecy surrounding Patriot Act surveillance, spent a fair amount of time at a recent speech suggesting that the public keep an eye on NSA's approach to location data.

But regardless of intelligence agencies interest in location data, yesterday's appeals court decision means the haze surrounding the privacy of location data will remain for the time being.