geofence, GPS or RFID

The police in the U.S. have started using warrants to tap into Google’s location database, known as Sensorvault, not only for information about suspects but also for “geofence” requests on an area where a crime occurred. The dragnet can include data from dozens or hundreds of devices — and can sometimes ensnare innocent people. geofence /ˈdʒiːə(ʊ)fɛns/ noun 1. a virtual geographic boundary, defined by GPS or RFID technology, that enables software to trigger a response when a mobile device enters or leaves a particular area. "they could put up a geofence around the building, meaning your phone disables itself when you enter it" verb 1. create a virtual geographic boundary around (an area) by means of GPS or RFID technology, enabling software to trigger a response when a mobile device enters or leaves the area. "the company has now geofenced the locations of 180,000 US schools"