are distinct from other physical possessions that may be searched incident to arrest without a warrant, because of the amount of personal data cell phones contain and the negligible threat they pose to law enforcement interests. Massachusetts prosecutors appealed this ruling to the Supreme Court. Opinion of the court The case of Riley v. California as heard before the Supreme Court combined two cases: Riley's case and United States v. Wurie. Riley argued that the digital contents of a smartphone do not threaten the safety of police officers, and that searches for which officers only have a belief that they may find evidence of a crime still violate constitutional rights. Stanford University law professor Jeffrey L. Fisher argued on behalf of Riley, and claimed that at least six courts held that the Fourth Amendment permits searches of this type, but that three courts did not. Therefore, a definitive Supreme Court precedent was needed. Fisher told the justices there are "very, very profound problems with searching a smartphone without a warrant" and that it was like giving "police officers authority to search through the private papers and the drawers and bureaus and cabinets of somebody's house." 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". Majority opinion This consolidated opinion addressed the appeals by both Riley and Wurie due to the similar questions raised. Chief Justice John Roberts delivered the opinion of the court, concluding that a warrant is required to search a mobile phone. Roberts wrote that when police search a suspect's phone without a warrant, they violate the warrantless search test established in Chimel v. California: Digital data stored on a cell phone cannot itself be used as a weapon to harm an arresting officer or to effectuate the arrestee's escape. Law enforcement officers remain free to examine the physical aspects of a phone to ensure that it will not be used as a weapon--say, to determine whether there is a razor blade hidden between the phone and its case. Once an officer has secured a phone and eliminated any potential physical threats, however, data on the phone can endanger no one. Although possible evidence stored on a phone may be destroyed with either remote wiping or data encryption, Roberts emphazied "the ordinary operation of a