Law enforcement authorities must obtain a warrant to search the cellphones of people they arrest, the U.S. Supreme Court said in a unanimous decision on Wednesday.

Writing for the majority, Chief Justice John Roberts said cellphone data is worthy of protection under the Fourth Amendment to the U.S. Constitution. Acquiring the information without a warrant is similar to rummaging through a person's entire belongings, he observed

"Our cases have recognized that the Fourth Amendment was the founding generation’s response to the reviled 'general warrants' and writs of assistance' of the colonial era, which allowed British officers to rummage through homes in an unrestrained search for evidence of criminal activity," Roberts wrote. "Opposition to such searches was in fact one of thedriving forces behind the Revolution itself."

"Modern cell phones are not just another technologicalconvenience. With all they contain and all they may reveal, they hold for many Americans 'the privacies of life,'" Roberts added. "The fact that technology now allows an individual to carry such information in his hand does not make the information any less worthy of theprotection for which the Founders fought. Our answer to the question of what police must do before searching a cell phone seized incident to an arrest is accordingly simple— get a warrant."

The decision came in a pair of cases, Riley v. California and US v. Wurie, in which authorities acquired information from cellphones without warrants and used that information to collect incriminating evidence.

Get the Story:
Get a warrant! Today’s cellphone privacy decision in Plain English (SCOTUSBlog 6/25)
Supreme Court says police must get warrants for most cellphone searches (The Washington Post 6/26)
Major Ruling Shields Privacy of Cellphones (The New York Times 6/26)
Cellphone Ruling Could Alter Police Methods, Experts Say (The New York Times 6/26)

Supreme Court Decision:
Riley v. California (June 25, 2014)