Geofence Warrants Are Unconstitutional, Federal Appeals Court Rules

Geofence warrants, the ability for police to get a broad amount of information about electronic devices in a given location, are unconstitutional under the Fourth Amendment, according to a ruling Friday from the Fifth Circuit Court of Appeals. The ruling is somewhat surprising given the fact that the Fifth Circuit Court of Appeals is considered the most conservative appeals court, as Ars Technica points out, typically giving preference to police over individual liberties.

The case, United States v. Smith, involves Mississippi men who were picked up for armed robbery in 2018. Police didn’t have any suspects for months and turned to a geofence warrant around the scene of the crime to find possible perpetrators, narrowed down to a roughly 1-hour period. Google handed over the information, according to the EFF, and police arrested two men whose phones showed they were in the area during that time.

As the EFF notes in quoting the ruling, the Fifth Circuit found that “the quintessential problem with these warrants” is that they will “never include a specific user to be identified, only a temporal and geographic location where any given user may turn up post-search.” The court called this “constitutionally insufficient.”

The ruling outlines the three steps that law enforcement needs to take during a geofence warrant, first providing Google with the time and location they wish to search. From there, Google finds the relatively anonymized data for every device talking to Google at that location and time, combing through millions of records. The second step involved police contextualizing and narrowing the data, looking at the anonymized list and figuring out which devices about which it wants to know more. The third step is when police ask for account-identifying information on the devices it identified as the most interesting. At that point, Google provides names and emails with the associated devices.

Interestingly, the new ruling differs from a Fourth Circuit ruling from last month that rejected a similar argument about geofence warrants. Back in 2019, police issued about 9,000 geofence requests for the year, jumping to 11,500 geofence warrants in 2020. In 2021, roughly 25% of all warrants issued to Google were geofence warrants, according to the ruling.

Google didn’t immediately respond to questions emailed Wednesday. We’ll update this post if we hear back.