The Fourth Amendment had been seemingly eroding since the early seventies. In Riley v. California, the Supreme Court of the United States addressed how far law enforcement can go when dealing with the contents of a cellphone. SCOTUS ruled unanimously that law enforcement must have a search warrant prior to investigating the contents of a cellphone and/or smartphone.
The analysis was logical and pragmatic. They found that cellphones are fundamentally different from most of the other items that may be found on someone's person and unique in that cellphones contain "a digital record of nearly every aspect of [people's] lives." SCOTUS determined that a warrant is necessary to pry into a person's lives so deeply. A true victory for protections afforded by the Fourth Amendment of the United States Constitution.