In the 2019 Virginia bank robbery case that became United States v. Chatrie, federal investigators had no eyewitness identification, no useful surveillance footage, and no recoverable fingerprints. What they had was a polygon drawn on a map and a request to Google for every Android device that crossed it during a 60-minute window. That single geofence query produced the suspect. Six years later, on April 30, 2025, the Fourth Circuit sat en banc to decide whether the technique itself was constitutional.