(CN) - In the first ruling of its kind, the 11th Circuit held that police need a warrant to obtain cellphone data used to pinpoint a suspect's location.
The three-judge panel in Atlanta ruled that Quartavius Davis, whose cell tower data placed him near the scenes of six robberies, had a Fourth Amendment right to keep his whereabouts private.
"While committing a crime is certainly not within a legitimate expectation of privacy, if the cell phone site location data could place him near those scenes, it could place him near any other scene," wrote U.S. District Judge David Sentelle, who was assigned to the three-judge panel.
"There is a reasonable privacy interest in being near the home of a lover, or a dispensary of medication, or a place of worship, or a house of ill repute."
Under the Stored Communications Act, law enforcement agents can ask cell phone service providers for records revealing which cell phone towers carried a suspect's calls. Investigators use this information to find out where a suspect made the call.
Davis' records revealed that he was near the six stores he was later convicted of robbing. He was sentenced to 162 years in prison.
He argued that the admission of the cell tower data -- based on a judge's order, not a warrant -- amounted to an unreasonable search in violation of the Fourth Amendment.
The 11th Circuit agreed on Wednesday, noting that its ruling marks the first of its kind nationwide.
Though the U.S. Supreme Court held in 2012 that police need a warrant to track suspects via GPS, it has not yet ruled on cellphone tower data.
The federal appeals court relied heavily on that decision, U.S. v. Jones
, to determine "that the privacy theory is not only alive and well, but available to govern electronic information of search and seizure in the absence of trespass."
"One's cell phone, unlike an automobile, can accompany its owner anywhere," Judge Sentelle wrote. "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."
Nathan Freed Wessler, the American Civil Liberties Union attorney who argued the case, called the panel's decision "a resounding defense of the Fourth Amendment's continuing vitality in the digital age."
"The court soundly repudiates the government's argument that merely by using a cellphone, people somehow surrender their privacy rights," he said in a statement
Despite the privacy finding, the judges declined to overturn Davis' convictions and sentence. They said police had acted in "good faith" at the time, adhering to existing federal law with "scrupulous obedience."
However, the court vacated and remanded a seven-year sentence enhancement for "brandishing" a firearm, because the jury "only found that Davis possessed a firearm."
The 11th Circuit's decision applies for now only in Florida, Georgia and Alabama.