supremecourtThe U.S. Supreme Court ruled unanimously today that law enforcement officers need to get a search warrant before they can rifle through the contents of someone’s smartphone.

Chief Justice John Roberts, who wrote the majority opinion, said that cell phones were vastly different from other items people might carry on them, especially in terms of the amount and breadth of data those phones contain.

“The term ‘cell phone’ is itself misleading shorthand; many of these devices are in fact minicomputers that also happen to have the capacity to be used as a telephone,” Roberts wrote. “They could just as easily be called cameras, video players, rolodexes, calendars, tape recorders, libraries, diaries, albums, televisions, maps, or newspapers.”

In the court’s view, that’s enough to require law enforcement to get a warrant before searching someone’s phone.

Lawyers for the State of California and the United States argued that cell phone searches are “indistinguishable” from warrantless searches of other items a person keeps on them, which are permitted under the Fourth Amendment. Roberts disagreed.

“That is like saying a ride on horseback is materially indistinguishable from a flight to the moon,” he wrote.

Law enforcement will still be able to search phones without a warrant under exigent circumstances – such as an imminent bomb explosion or child abduction – but aside from that, cops will need a warrant if they want to get access to a phone.

Today’s ruling leaves one thing unclear: whether or not making a copy of a phone’s contents for a later search would count as a search itself. It’s fairly standard practice for law enforcement officers to make a forensic copy of an electronic device’s contents in the course of executing a search warrant, and then search that copy for anything relevant.

The ruling comes alongside another decision by the court to smack down Aereo, a startup that allowed users to rent an antenna in a central datacenter and then stream television content to their computers or mobile devices.

Check out the full opinion embedded below.

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