Tech Crunch: US appeals court rules geofence warrants are unconstitutional

Civil liberties and privacy advocates applauded the ruling, which effectively makes the use of geofence warrants unlawful across the three U.S. states for now.

Geofence warrants, also known as “reverse” search warrants, allow police to draw a shape on a map, such as over a crime scene, and demand that Google (or any other company that collects user locations) search its entire banks of location data for any phone or device that was in that area at a specific point in time.

But critics have long argued that geofence warrants are unconstitutional because they can be overbroad and include information on entirely innocent people.

The court case centers on an armed robbery of a U.S. Postal Service worker in Mississippi in February 2018, in which police used a geofence warrant to identify the individuals suspected of the robbery.

The Fifth Circuit’s opinion comes to a different conclusion than a similar case heard last month in the Fourth Circuit, which covers North Carolina, Virginia and West Virginia. That ruling found that accessing Google’s stores of location data does not count as a search and upheld the legality of geofence warrants across those states.

In its case, the Fifth Circuit disagreed and found that police seeking data from Google’s vast stores of location data for a criminal suspect does in fact constitute a search. But because the bank of data is so big, and because the entire database has to be scanned, the court ruled that there is no legal authority capable of authorizing a search, per a blog post by law professor Orin Kerr analyzing the ruling.

The court said in its ruling, its emphasis included: “This search is occurring while law enforcement officials have no idea who they are looking for, or whether the search will even turn up a result. Indeed, the quintessential problem with these warrants is that they never include a specific user to be identified, only a temporal and geographic location where any given user may turn up post-search. That is constitutionally insufficient.”

While the Fifth Circuit ruled that geofence warrants are unconstitutional, the court concluded that the police department had acted in good faith when seeking the warrant for the location data held by Google, and upheld the defendant’s conviction. The court said, in part because the use of geofence warrants were novel at the time and the department asked other agencies for legal guidance prior to submitting the warrant, the evidence should not be suppressed in this case.

Kerr, in his analysis, said the ruling “raises questions of whether any digital warrants for online contents are constitutional.”

Because tech companies, like Google, Uber, Snap and others, collect and store huge amounts of its users’ location data and histories on its servers, this data can be obtained by law enforcement; if the data didn’t exist, the problem would be moot. The use of geofence warrants has rocketed in recent years, at one point amounting to about one-quarter of all U.S. legal demands the company received.

Google said late last year that it would begin storing users’ location data on their devices, making geofence warrants less useful for law enforcement.