In San Diego, police stopped David Riley for driving with expired registration tags. After learning Riley's license was suspended, officers impounded his car and conducted an inventory search, during which they found two handguns. Riley was arrested for weapons offenses. An officer seized Riley's smartphone from his pants pocket and, without a warrant, examined its contents at the scene, observing indications of gang affiliation. Later at the station, a detective conducted a more thorough review of the phone, accessing photographs and videos that appeared to connect Riley to a recent gang-related shooting. Those digital contents were used to enhance and support criminal charges. In a companion case, United States v. Wurie, Boston police arrested Brima Wurie after observing a drug sale. Officers seized his flip phone and noticed repeated calls from a contact labeled "my house." Without a warrant, they viewed the call log and traced the number to an address, then obtained a warrant to search the apartment, where they found drugs, cash, and a firearm. The First Circuit suppressed the phone-derived evidence, deepening a split over whether the search-incident-to-arrest doctrine permits warrantless searches of cell phone data. The Supreme Court granted certiorari and consolidated the cases.
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.
The Court began with the two rationales underpinning search-incident-to-arrest doctrine from Chimel v. California: officer safety and the preservation of evidence. First, officer safety does not justify a digital search. Although an arrestee may conceal weapons in physical containers, the data on a phone cannot itself threaten officers. Officers may physically secure the phone to neutralize any potential hazard, but that does not extend to rummaging through digital files. Second, the government's evidence-preservation rationale did not support categorical warrantless searches of phone data. Concerns about remote wiping or data encryption were deemed speculative and manageable by less intrusive means (e.g., turning the phone off, removing the battery, using a Faraday bag), and the exigent-circumstances doctrine remains available if specific, articulable facts show an imminent risk of evidence destruction or a pressing need. The Court rejected analogies between a phone and a traditional "container" under United States v. Robinson. Modern phones are not just containers but "minicomputers" that hold a vast and revealing mosaic of information—photos, messages, browsing history, location data, health and financial records—that collectively expose the "privacies of life." The sheer quantity and qualitative breadth of digital data, coupled with its retrospective and pervasive nature, elevates the privacy interests well beyond those implicated by pocket contents or paper documents. Nor does the possibility that some data may be stored remotely (in the cloud) support warrantless searches; the search-incident doctrine does not authorize fishing expeditions into on-device or cloud-linked accounts simply because the device is on the person of an arrestee. Balancing governmental interests against privacy, the Court adopted a clear rule: officers must get a warrant before searching a phone's digital content. This rule is administrable, respects core Fourth Amendment values, and leaves room for genuine exigencies (e.g., an immediate threat to life, hot pursuit, or imminent evidence destruction) to justify prompt action without a warrant.
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.
Riley v. California establishes a bright-line Fourth Amendment rule for the digital era: absent exigent circumstances, police must get a warrant to search the data on a cell phone seized incident to arrest. By distinguishing digital information from physical containers, the Court recalibrated the balance between law enforcement needs and personal privacy in a technologically saturated world.