US Supreme Court strikes a blow for privacy: You need a warrant to search someone's cellphone!

Chief Justice John Roberts writing for the court, said the vast amount of data contained on modern cellphones must be protected from routine inspection.

The court heard arguments in April in two cases on the issue, but issued a single decision.

The first case, Riley v. California, No. 13-132, arose from the arrest of David L. Riley, who was pulled over in San Diego in 2009 for having an expired car registration. The police found loaded guns in his car and, on inspecting Mr. Riley’s smartphone, entries they associated with a street gang.

A more comprehensive search of the phone led to information that linked Riley to a shooting. He was later convicted of attempted murder and sentenced to 15 years to life in prison. A California appeals court said neither search had required a warrant.

The second case, United States v. Wurie, No. 13-212, involved a search of the call log of the flip phone of Brima Wurie, who was arrested in 2007 in Boston and charged with gun and drug crimes. The federal appeals court in Boston last year threw out the evidence found on Wurie’s phone.

News organisations, including The New York Times, filed a brief supporting Riley and Wurie in which they argued that cellphone searches can compromise news gathering.

The courts have long allowed warrantless searches in connection with arrests, saying they are justified by the need to protect police officers and to prevent the destruction of evidence. The Justice Department, in its Supreme Court briefs, said the old rule should apply to the new devices.

Others say there must be a different standard because of the sheer amount of data on and available through cellphones.

“Today, many Americans store their most personal ‘papers’ and ‘effects’ in electronic format on a cellphone, carried on the person,” Judge Norman Stahl wrote for a divided three-judge panel in . Wurie’s case, quoting the words of the Fourth Amendment.