In a blockbuster 5-4 decision issued today, the U.S. Supreme Court ruled that warrantless government tracking of cellphone users via their cellphone location records violates the Fourth Amendment. “A person does not surrender all Fourth Amendment protection by venturing into the public sphere,” declared the majority opinion of Chief Justice John Roberts. “We decline to grant the state unrestricted access to a wireless carrier’s database of physical location information.”
The case is Carpenter v. United States. It arose after the after FBI obtained, without a search warrant, the cellphone records of a suspected armed robber named Timothy Carpenter. With those records, law enforcement officials identified the cell towers that handled his calls and then proceeded to trace back his whereabouts during the time periods in which his alleged crimes were committed. That information was used against Carpenter in court.
The central issue in the case was whether Carpenter had a “reasonable expectation of privacy” in the information contained in those records, or whether he had forfeited such privacy protections by voluntarily sharing the information with his cellular service provider. As the Supreme Court put it in United States v. Miller (1976) and Smith v. Maryland (1979), “a person has no legitimate expectation of privacy in information he voluntarily turns over to third parties.”
Read the rest at reason.com.