Even disregarding the content of a call, cell phones reveal a wealth of information about the person making the call. Called "metadata," that bundle of other information can include the time the call took place, the call duration, the company that carried the call, and the cell towers that transmitted the call, giving a rough approximation of the callers' physical locations. Last summer news broke that the U.S. government was storing cell phone metadata. Yesterday, the Eleventh Circuit Court of Appeals ruled in USA v. Quartavious Davis that Fourth Amendment protections against against unreasonable searches and seizures and the issuing of warrants without probable cause extend to cell phone location data.
The case concerns Quartavious Davis, convicted of armed robberies after the police used cell phone location data to place him in the vicinity of the other robbers. Police obtained this location information from the cell phone companies through court order, which has a much lower threshold for reasonable cause than that required for a warrant.
Here's the crucial nugget at the heart of the decision:
Supportive of this proposition is the argument made by the United States to the jury. The prosecutor stated to the jury “that obviously Willie Smith, like [Davis], probably had no idea that by bringing their cell phones with them to these robberies, they were allowing [their cell service provider] and now all of you to follow their movements on the days and at the times of the robberies . . . .” Just so. Davis has not voluntarily disclosed his cell site location information to the provider in such a fashion as to lose his reasonable expectation of privacy.
In short, we hold that cell site location information is within the subscriber’s reasonable expectation of privacy. The obtaining of that data without a warrant is a Fourth Amendment violation.
The decision is set up by a Third Court ruling from 2010.
The Third Circuit went on to observe that “a cell phone customer has not ‘voluntarily’ shared his location information with a cellular provider in any meaningful way.” That circuit further noted that “it is unlikely that cell phone customers are aware that their cell phone providers collect and store historical location information.” Therefore, as the Third Circuit concluded, “when a cell phone user makes a call, the only information that is voluntarily and knowingly conveyed to the phone company is the number that is dialed, and there is no indication to the user that making that call will also locate the caller.” Even more persuasively, “when a cell phone user receives a call, he hasn’t voluntarily exposed anything at all.”
Much of the legalese around this is tied up both in privacy precedents and an understanding of what information is private and what is held by third parties. As for the technology, location data built up over the course of a day can reveal in aggregate much about an individual that they may wish to keep private. Last year, MIT researchers published a study showing it is possible to identify people with 95 percent accuracy using just four points from a location tracking cell phone.
While the Davis case sets an important precedent, the appeals court notes in their ruling that because there is no evidence the police "evidenced anything other than good faith," the court does not see fit to reverse their error. Instead, USA v. Quartavious Davis provides a ruling for the future that asserts fourth amendment protections over cell phone location data. Should this precedent hold, in the future police will need warrants, not court orders, to obtain such information.
