WASHINGTON, DC — If you carried a cell phone past the wrong street corner at the wrong moment, police could already have your movements, your digital trail, and your identity—without ever suspecting you of a crime. That is the reality of geofence warrants, a powerful surveillance tool whose use by police is now being challenged …WASHINGTON, DC — If you carried a cell phone past the wrong street corner at the wrong moment, police could already have your movements, your digital trail, and your identity—without ever suspecting you of a crime. That is the reality of geofence warrants, a powerful surveillance tool whose use by police is now being challenged …