A geofence search is a law enforcement technique used to request data from technology companies about all mobile devices that were present within a defined geographic area during a specific time frame. This method relies on location data collected by smartphones and other devices, typically from apps or operating system services. Authorities use geofence searches to identify potential suspects or witnesses by casting a digital net over a crime scene or area of interest. While effective for investigations, geofence searches raise significant privacy concerns because they can collect information on individuals who are not connected to any crime, leading to debates about their legality and scope.