In Riley v. California (2013), the U.S Supreme Court unanimously held that law enforcement must obtain a warrant before conducting a search of digital information on an arrested individual's cell phone, under the Fourth Amendment protection against unreasonable searches and seizures. The case involved David Leon Riley, who was stopped for a traffic violation in San Diego and later arrested on weapons charges after police found loaded guns in his car. Police then searched his smartphone without obtaining a warrant, uncovering evidence linking him to gang-related activities and an earlier shooting incident. This evidence led to further charges and conviction at trial court level; however, this decision was overturned by the Supreme Court ruling which established that searching data on mobile phones during arrests requires warrants due to privacy concerns.

In the Supreme Court case Riley v. California, there was no formal dissenting opinion as the decision was unanimous. However, Justice Alito concurred in part and concurred in judgment but expressed reservations about the broad implications of the ruling. He agreed with the majority that police should generally obtain a warrant before searching digital information on a cell phone seized incident to arrest, but he questioned whether this rule should apply to all types of data stored on modern cell phones or other similar devices. He suggested that it might be necessary for future cases to distinguish between different types of personal data based on their privacy implications and potential relevance to law enforcement investigations.