On the other hand, the First Circuit and the Supreme Courts of Florida and Ohio disagreed and ruled that police needed a warrant to search the information on a suspect's phone.

[3] California had also proposed a state statute requiring police to obtain a warrant before searching the contents of "portable electronic devices".

"[6] In Chimel v. California (1969), the Supreme Court ruled that if the police arrest someone, they may search the body of the person without a warrant and "the area into which he might reach" in order to protect material evidence or the officers' safety.

The San Diego Police Department's policy at the time was to impound a vehicle after stopping a driver with a suspended license in order to prevent them from driving again.

Based in part on the pictures and videos recovered from the cell phone, police charged Riley in connection with the gang shooting.

"[14] Fisher warned that it could open up "every American's entire life to the police department, not just at the scene but later at the station house and downloaded into their computer forever".

Chief Justice John Roberts delivered the opinion of the court, concluding that a warrant is required to search a mobile phone.

[19]Justice Samuel Alito wrote an opinion concurring in the judgment, noting that "we should not mechanically apply the rule used in the predigital era to the search of a cell phone.

"[20] However, in trying to find a balance between law enforcement and privacy issues, Alito expressed concern that the majority opinion would create anomalies: "Under established law, police may seize and examine [hard copies of information] in the wallet without obtaining a warrant, but under the Court's holding today, the information stored in the cell phone is out.

"[21] Alito further suggested that Congress or state legislatures may need to consider new laws that draw "reasonable distinctions based on categories of information or perhaps other variables",[22] otherwise "it would be very unfortunate if privacy protection in the 21st century were left primarily to the federal courts using the blunt instrument of the Fourth Amendment".

[23] The Supreme Court's ruling in Riley v. California was generally praised for addressing the challenges presented by new technologies,[24] but with mixed reviews concerning its impact on privacy law and police procedure.