A geofence warrant — sometimes called a reverse location warrant — orders a company, usually Google, to disclose the identity of every device that was within a defined geographic area during a defined time period. Police use them to find suspects when they have a location but not a name: a crime scene, a protest, an attack. The warrant casts a digital net over an area and then asks who was inside.
The process works in three steps: police ask a company for anonymized location data from all devices in the area, identify devices connected to the crime, and then request the identity of specific users. Google has disclosed its geofence warrant volume ran into the tens of thousands annually at its peak.
In 2025, the Supreme Court granted certiorari in cases raising whether geofence warrants violate the Fourth Amendment. The core constitutional question is whether people have a reasonable expectation of privacy in the location data their phones automatically generate — even if they never consciously shared it. Some federal courts have struck down geofence warrants as unconstitutional general warrants; others have allowed them with probable cause and particularity requirements.
Geofence warrants can expose anyone who was in a public place — a demonstration, a neighborhood, a church — to police investigation without any individual suspicion. Civil rights organizations have documented wrongful investigations from geofence data. The same authority that finds criminals can surveil political protesters and journalists.
People assume geofence warrants require probable cause about specific individuals. They don't — police need only probable cause that a crime occurred at a location. Everyone whose phone was in that location becomes a subject of inquiry. Courts are still deciding whether this dragnet approach meets Fourth Amendment standards.
Geofence warrants can expose anyone who was in a public place — a demonstration, a neighborhood, a church — to police investigation without any individual suspicion. Civil rights organizations have documented wrongful investigations from geofence data. The same authority that finds criminals can surveil political protesters and journalists.
People assume geofence warrants require probable cause about specific individuals. They don't — police need only probable cause that a crime occurred at a location. Everyone whose phone was in that location becomes a subject of inquiry. Courts are still deciding whether this dragnet approach meets Fourth Amendment standards.