Carpenter v. United States

The Court held that accessing historical cell phone location data is a Fourth Amendment search requiring a warrant.

Overview

The FBI obtained 127 days of Timothy Carpenter's cell site location information without a warrant under a stored communications statute, placing him near robbery scenes. Chief Justice Roberts, for a 5-4 majority, held that individuals have a reasonable expectation of privacy in the record of their physical movements captured by cell phones, declining to apply the third-party doctrine mechanically. Carpenter recognized that sweeping technological change requires new Fourth Amendment analysis and now anchors digital privacy doctrine for location data, smart devices, and beyond.