Court allows warrantless searches in "exigent" cases like abductions, bomb plots.

The Supreme Court on Wednesday ruled unanimously that the authorities generally may not search the mobile phones of those they arrest unless they have a court warrant.

"Our answer to the question of what police must do before searching a cell phone seized incident to an arrest is accordingly simple—get a warrant," Chief Justice John Roberts wrote. [PDF]

It's perhaps the biggest digital-age privacy decision the high court has rendered following its 2012 ruling that the authorities usually need warrants to affix GPS trackers to a suspect's vehicle.

President Barack Obama's administration and prosecutors from states across the country had lobbied the high court in briefs to allow police officers to be able to search arrestees' gadgets—not just mobile phones—without a warrant. The justices declined to do so, saying "privacy comes at a cost."

"Modern cell phones, as a category, implicate privacy concerns far beyond those implicated by the search of a cigarette pack, a wallet, or a purse. A conclusion that inspecting the contents of an arrestee’s pockets works no substantial additional intrusion on privacy beyond the arrest itself may make sense as applied to physical items, but any extension of that reasoning to digital data has to rest on its own bottom," the court ruled.

The court added: "Prior to the digital age, people did not typically carry a cache of sensitive personal information with them as they went abouttheir day. Now it is the person who is not carrying a cellphone, with all that it contains, who is the exception."

The court suggested that it would not tolerate warrantless mobile phone tracking, either. The lower courts are mixed on whether the authorities need a warrant to track a suspect's every move.

... it is no exaggeration to say that many of the more than 90% of American adults who own a cell phone keep on their person a digital record of nearly every aspect of their lives—from the mundane to the intimate. See Ontario v. Quon, 560 U. S. 746, 760 (2010). Allowing the police to scrutinize such records on a routine basis is quite different from allowing them to search a personal item or two in the occasional case.

Although the data stored on a cell phone is distinguished from physical records by quantity alone, certain types of data are also qualitatively different. An Internet search and browsing history, for example, can be found on an Internet-enabled phone and could reveal an individual’s private interests or concerns—perhaps a search for certain symptoms of disease, coupled with frequent visits to WebMD. Data on a cell phone can also reveal where a person has been. Historic location information is a standard feature on many smart phones and can reconstruct someone's specific movements down to the minute, not only around town but also within a particular building.

The justices said that awaiting for a judge to issue a warrant is not needed in every case if there are "exigent," or emergency circumstances:

In light of the availability of the exigent circumstances exception, there is no reason to believe that law enforcement officers will not be able to address some of the more extreme hypotheticals that have been suggested: a suspect texting an accomplice who, it is feared, is preparing todetonate a bomb, or a child abductor who may have information about the child’s location on his cell phone. The defendants here recognize—indeed, they stress—that suchfact-specific threats may justify a warrantless search of cell phone data.

This is a very good move towards protecting our rights. I was very mad at the supreme court over the Aereo case, but happy about this one.

This is great because each person has their own privacy