The U.S. Court of Appeals for the Sixth Circuit held, in United States v. Carpenter, that government access to historic cell-site records, which show what cell towers a phone was connected to (and thus its owner’s rough location), is not a search under the Fourth Amendment and so a warrant is not required. The court reasoned that individuals know that cell carriers record users’ location information for legitimate business purposes, and so forsake any reasonable expectation of privacy when they voluntarily transmit their location to their carriers. In so holding, the Sixth Circuit joins the Fifth Circuit and en banc Eleventh Circuit. A Fourth Circuit panel, in contrast, has ruled that a warrant is required for this data, but that decision is currently being reviewed by the full Fourth Circuit.