Carpenter v. United States

Carpenter v. United States, 585 U.S. 296 (2018), is a landmark decision of the United States Supreme Court.

Police obtained cell-site location information (CSLR) from Timothy Carpenter’s wireless carriers without a warrant, covering 12,898 location points over 127 days. They used this data to place Carpenter near the scene of a series of robberies. Carpenter argued that obtaining this data without a warrant violated the Fourth Amendment.

Significance

Chief Justice Roberts’ 5-4 opinion held that the government’s acquisition of historical cell-site records constitutes a Fourth Amendment search requiring a warrant. The Court applied the ‘reasonable expectation of privacy’ test and found that individuals have a privacy interest in the whole of their physical movements over time. The ’third-party doctrine’ — that information voluntarily shared with a third party lacks Fourth Amendment protection — did not apply because cell phone location records are ‘deeply revealing.’ The decision marked a significant expansion of Fourth Amendment protection in the digital age.

Category

US Federal Case Law