The U.S. Supreme Court recently heard arguments over a law enforcement technique that asks tech companies to search vast caches of location data to identify devices near a crime scene. At issue is whether “geofence” warrants are a legitimate investigative tool, an unconstitutional digital dragnet, or both.
Geofencing allows authorities to draw a virtual boundary around a place and obtain a warrant compelling a company to identify any user devices that crossed that perimeter during a specified time window. The case before the justices centered on Google Location History, a service that in 2019 logged users’ locations roughly every two minutes by combining multiple signals. At the time, about one-third of Google users — roughly 500 million people — had opted into storing these records in Google’s cloud, where they could be produced to law enforcement with a warrant.
Supporters of geofence warrants say they are a practical investigative tool when other leads have failed. Stanford law professor Orin Kerr described them as a kind of “investigative lottery ticket” that can yield leads. The government also points out that similar techniques were used after the Jan. 6 Capitol attack to separate those who unlawfully breached the building from people who were lawfully present.
But the technique raises significant Fourth Amendment questions. The text and history of the Constitution require that searches be reasonable and that warrants be particularized and issued by neutral magistrates. Critics argue geofence warrants sweep up large numbers of innocent people — commuters, worshipers, patients, or protestors — and risk chilling lawful behavior by making people wary of participating in public life.
The present case stems from a 2019 Midlothian, Virginia, bank robbery in which investigators, after months with no suspect, obtained a geofence warrant covering an area about the size of three football fields and sought data for one hour before and after the crime. Google initially produced 19 devices, later negotiated with police to narrow the list to nine and then three devices to be unmasked. One of those identified, Okello Chatrie, was arrested; the other two were apparently bystanders.
The government contends that users who enabled Location History waived any reasonable expectation of privacy in those records, and that a defendant who took no steps to hide his whereabouts cannot claim a privacy interest. Defense lawyers counter that compelling a company to search millions of accounts effectively authorizes a general, nonparticularized search — precisely the sort of broad warrant the Founders opposed.
Justice Department veteran Michael Dreeben urged the court to treat the issue as twofold: whether geofence searches fall under the Fourth Amendment at all, and whether voluntarily storing location records with a provider forfeits privacy protections for that information. He acknowledged privacy risks but argued cloud-based records used for legitimate services should still have protection against arbitrary government intrusion.
How common geofence warrants are is unclear. A 2020 law review article estimated about 11,500 geofence warrants served on Google that year, a figure that has drawn attention from privacy advocates. Google has already adjusted some practices — moving certain storage to users’ devices — and has filed briefs urging courts to treat digital records with the same safeguards as physical records and to require individualized warrants.
Legal observers say the Court’s decision could have wide-ranging consequences. A ruling that restricts geofence warrants or requires stricter particularity would constrain many investigative practices; a ruling that allows them would preserve a powerful tool for police but alarm privacy advocates who fear expanded surveillance. A decision is expected by early summer.