Police officers need a warrant if they want to search the cell phones of people placed under arrest, the U.S. Supreme Court ruled  in a unanimous decision Wednesday. The decision was seen as a boon to privacy advocates.

“Modern cell phones are not just another technological convenience. With all they contain and all they may reveal, they hold for many Americans ‘the privacies of life,’” Chief Justice John Roberts wrote in the majority opinion rulings of Riley v. California and U.S. v. Brima Wurie, two related cases centering on whether police can search digital information on a cell phone without a warrant.  

“The fact that technology now allows an individual to carry such information does not make the information any less worthy of the protection 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,” Roberts said.

The court said there are exceptions to the ruling, including cases where a child abductor may have information about the child’s whereabouts on their phone or a suspect who texted an accomplice about detonating a bomb.

Read the full ruling below:

  Supreme Court Cell Phone Ruling