The U.S. Supreme Court ruled unanimously Wednesday that unless police have a warrant, they generally cannot search data on a cellphone seized from someone who has been arrested.
The decision is seen as a sweeping win for privacy advocates.
"Modern cell phones are not just another technological convenience," Chief Justice John Roberts wrote. "With all they contain and all they may reveal, they hold for many Americans 'the privacies of life.'
As NPR legal affairs correspondent Nina Totenberg reported in April:
"The courts have long allowed police to search people without a warrant when making an arrest. But those searches have been limited by the amount of information individuals could carry on their persons.
"Now, suddenly, with the advent of the smartphone, allowing a search of that phone without a warrant allows police to search more information than most people keep in their houses."
The first of two related cases, Riley v. California, centered on David Riley, who was pulled over in 2009 in San Diego for driving with expired tags. As Nina reported:
"When his car was impounded and inventoried, police found guns under the hood. An initial search of Riley's cellphone indicated he might be involved in gang activity.
"Two hours later, a gang investigator went through the digital files and downloaded contacts, videos and photos. Some of that information was later used to convict Riley of several felonies."
Riley's lawyer told the court in April that the Founding Fathers hadn't intended such wide-ranging warrantless searches. But the state of California and the Obama administration had contended that cellphones should have no greater protection than other objects police find.
On Wednesday, the Supreme Court disagreed.
"The fact that technology now allows an individual to carry such information in his hand does not make the information any less worthy of the protection for which the Founders fought," Roberts wrote.
But the court did say that warrantless searches could be permitted in some extraordinary circumstances as in instances of child abductions or bomb threats.
The second case, U.S. v Wuhrie, involved a defendant whose flip-phone call log was searched by police. The Associated Press reports on the background to that case from Boston:
"Police arrested Brima Wurie on suspicion of selling crack cocaine, checked the call log on his flip phone and used that information to determine where he lived. When they searched Wurie's home and had a warrant, they found crack, marijuana, a gun and ammunition. The evidence was enough to produce a conviction and a prison term of more than 20 years.
An appeals court threw out the evidence found on Wuhrie's phone but left in place a drug conviction that did not depend on the tainted evidence. The Obama administration had appealed that ruling because it wanted to preserve warrantless searches following an arrest.
On Wednesday, the Supreme Court upheld the lower court's ruling.