The U.S. Court of Appeals for the Fifth Circuit has ruled that geofence warrants, which allow police to collect data on individuals’ whereabouts, violate the Fourth Amendment.

TechCrunch reported the decision today.

Geofence warrants enable law enforcement officials to identify who was in the vicinity of a crime scene when the offense was committed. In most cases, such warrants are issued to Google LLC because the company collects a significant amount of location data from Android devices. Moreover, the iOS versions of the Alphabet Inc. unit’s search engine and other services allow it to track Apple Inc. handsets. 

The Fifth Circuit, the court that found geofence warrants to be unconstitutional, fields cases from Louisiana, Mississippi and Texas. It issued the landmark ruling in connection with a case called United States v. Smith that focused on the 2018 armed robbery of a U.S. Postal Service truck. Police used a geofence warrant to identify the suspects.

The Fifth Court found that geofence warrants are general warrants, which place almost no limitations on the search or arresting authority of law enforcement officials. General warrants are prohibited under the Fourth Amendment. One of the considerations that factored into the judges’ decision was the large amount of personal data police sift through when examining location data from Google. 

The search giant associates the location data it collects from a user’s smartphone with a so-called device ID, an identifier unique to that handset. Geofence warrants compel Google to hand over all the device IDs that appeared in a given location around the time a crime was committed. The warrant issued in the United States v. Smith case covered an approximately 0.3-square-mile area around a post office.

The initial dataset of device IDs that Google hands over to authorities is anonymized. Law enforcement officials can ask the search giant to provide “additional de-identified location information for a certain device to determine whether that device is actually relevant to the investigation,” the Fifth Circuit’s ruling detailed. If relevance is established, officials may request the names of the device’s users and their email addresses.

“Geofence warrants effectively ‘work in reverse’ from traditional search warrants,” the Fifth Court’s ruling stated. “This court cannot forgive the requirements of the Fourth Amendment in the name of law enforcement.” The decision tentatively makes the use of geofence warrants unlawful in Louisiana, Mississippi and Texas. 

Digital rights group Electronic Frontier Foundation welcomed the ruling in a statement. “EFF applauds this decision because it is essential that every person feels like they can simply take their cell phone out into the world without the fear that they might end up a criminal suspect because their location data was swept up in an open-ended digital dragnet,” the group stated. 

Photo: weiss paarz/Flickr