Investigators must obtain a search warrant from a judge in order to obtain cellphone tower tracking data that is widely used as evidence to show suspects were in the vicinity of a crime, a federal appeals court ruled Wednesday.

In the first ruling of its kind nationally, a three-judge panel of the 11th U.S. Circuit Court of Appeals determined people have an expectation of privacy in their movements and that the cell tower data was part of that. As such, obtaining the records without a search warrant is a violation of the Fourth Amendment’s ban on unreasonable searches and seizures, the judges ruled.

“While committing a crime is certainly not within a legitimate expectation of privacy, if the cell site location data could place him near those scenes, it could place him near any other scene,” the judges wrote. “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.”

The ruling does not block investigators from obtaining the records that show which calls are routed through specific towers as well as which phones are nearby. It simply requires a higher legal showing of probable cause that a crime is or was being committed to obtain a search warrant rather than a less-strict court order.

“The court soundly repudiates the government’s argument that merely by using a cellphone, people somehow surrender their privacy rights,” said ACLU attorney Nathan Freed Wessler, who argued the case. He said no other federal appeals court had ruled on the issue.

The U.S. Supreme Court, while also not yet ruling on cellphone tower records, in 2012 decided that secretly attaching GPS devices to track suspects’ vehicles also constituted a search under the Fourth Amendment. The justices did not, however, decided that investigators must always obtain a search warrant to do that.

The 11th Circuit decision, which relied heavily on the GPS decision, applies for now only in Florida, Georgia and Alabama. The judges said other circuit courts had considered similar arguments, but not in a criminal case. Ultimately the issue will likely have to be resolved by the Supreme Court.

“I think this is very big, because this really takes away from cops and prosecutors what had been a very powerful tool,” said Robert Jarvis, a law professor at Nova Southeastern University. “Now you have to really show that you have reasonable grounds to believe criminal activity is taking place and that there is no other way to get the information.”

The ruling came in the Miami case of Quartavious Davis, who is serving a 162-year prison sentence for a string of violent armed robberies. The judges refused to overturn his convictions and sentence over the cellphone tracking issue. They applied a “good faith” exception preventing authorities from being punished for relying on a law later found unconstitutional.

The cellphone tower data used at trial placed Davis near six of the armed robberies for which he was ultimately convicted. Investigators analyzed tower data over a 67-day period for four suspects, including more than 11,000 data points for Davis himself.

The appeals court did agree to a separate argument by Davis that his sentence was improperly enhanced for “brandishing” a firearm, sending the case back to Miami district court for resentencing on that issue alone.

(AP)