Federal investigators used a geofence warrant to obtain anonymized and then identifying location information for devices detected near the scene of a bank robbery. The district court concluded that the warrant violated the Fourth Amendment but admitted the evidence under the good-faith exception; the Fourth Circuit affirmed on the different ground that obtaining the data was not a search. The Supreme Court held that government acquisition of the historical location information constituted a Fourth Amendment search because the data exposed a person’s movements through information generated by a cellphone and maintained by a service provider. The judgment was vacated and the case remanded for consideration of the warrant and remedy questions under the proper constitutional framework.