573 U.S. 373 (2014) (U.S. Supreme Court)
Riley v. California is a landmark Fourth Amendment decision that reshaped search-and-seizure law for the digital age.
Whether, under the Fourth Amendment, police may search the digital contents of a cell phone seized from an arrestee without a warrant under the search-incident-to-arrest exception.
Police generally must secure a warrant before searching digital information on a cell phone seized from an individual who has been lawfully arrested. The traditional search-incident-to-arrest exception does not extend to the phone's digital data, though exigent circumstances may justify a warrantless search in a particular case.
The Supreme Court unanimously held that the search-incident-to-arrest exception does not authorize warrantless searches of the digital contents of cell phones. Officers must ordinarily obtain a warrant, absent exigent circumstances.
Riley modernized Fourth Amendment doctrine for digital devices, clarifying that personal privacy interests in smartphones are categorically different from physical containers. It sets a bright-line rule that protects vast amounts of sensitive data from warrantless searches during routine arrests, while preserving an exigent-circumstances safety valve. For law students, Riley is essential for understanding how traditional exceptions (search incident to arrest, inventory, exigency) interact with digital technology and for framing analyses in later digital privacy cases, including Carpenter's treatment of historical cell-site location information. It also guides police practices nationwide, prompting widespread adoption of warrants, Faraday techniques, and data-handling protocols.