POLICE SURVEILLANCE DEALT A SETBACK

    Yesterday, the Supreme Court handed down its decision in the case of Carpenter v. United States, reversing and remanding Mr. Carpenter's conviction for armed robbery. That conviction had been obtained in part by using detailed Cell Site Location Information (ACSLI), which the police acquired without a warrant and which showed Mr. Carpenter's whereabouts at the time of various crimes. This procedure, which allows law enforcement ready access to the whereabouts of every American with a cell phone every minute of his life, was authorized by Congress in the Stored Communications Act of 1986.