Not long ago, police could search a cell phone whenever they liked. The Supreme Court, however, put a stop to that this summer with a 9-0 ruling that requires cops to get a warrant before they can access the trove of evidence — contacts, photos, videos and more — that now resides in every person’s pocket.

For police, though, that warrant rule is now one of two obstacles standing in the way of a search. The other is the new prevalence of passcodes, which most people use to lock their phones, and which are harder to get around than ever before thanks to expanded encryption. The result is a new controversy over when cell phone users must assist the police.

It goes like this: the Fourth, the Fifth

Recent legal battles over cell phone searches have focused (correctly) on the Fourth Amendment, which is how the U.S. Constitution protects people against unreasonable search and seizure — specifically, by requiring cops to get a warrant for performing most type of searches. In light of the Supreme Court’s recent ruling, however, that question has been largely put to rest.

Now the debate is turning instead to the Fifth Amendment, which protects suspects from having to testify against themselves. While the historical right to “plead the Fifth” is well understood (it prevented soldiers from getting a confession by beating someone up), its role when it comes to cell phones is less obvious.

But as it turns out, it’s the Fifth Amendment that’s central to answering the question of whether cops, provided they have a valid warrant, can force a suspect to unlock a phone — and whether the act of unlocking is an illegal form of coerced evidence.

A court ruling in Virginia directly addressed that question last week, and the answer is unusual: if the phone has a “touch-to-unlock” feature, suspects must use their finger or thumb to unlock the device (or otherwise provide a fingerprint that will let police do so) but, thanks to the Firth Amendment, they can’t be compelled to turn over the phone’s passcode too.

For now, the effect of the ruling will be limited since only a handful of newer cell phone models, such as the iPhone 6 and the Galaxy S 5, have the touch ID feature. But it could soon have broad implications at a time when device makers of all stripes are moving to biometric authentication systems.

News of the ruling was first published last week by the Virginia Pilot, but now the ruling itself is now available. The decision, and related commentary by legal bloggers, provides more details about the distinction between the two types of unlocking, and how it relates to the larger debate over encryption.

What is “extortion of information?”

The Virginia court case is about videos on a man’s cell phone that allegedly show him beating and having sex with [RAPING?] a woman. The police used a warrant to seize the phone but could not view the videos since the cell phone was locked by a passcode, and the man refused to unlock it.

In ordering the man to provide a thumbprint, the court said giving a print was no different than other physical acts that police routinely require:

“Even though the act may provide incriminating evidence, a criminal suspect may be compelled to put on a shirt, to provide a blood sample or handwriting exemplar, or to make a recording of his voice,” wrote the court, citing a Supreme Court case from 2000 (my emphasis).

It turns out, though, that such actions are legally distinct from those that force a suspect to “disclose the contents of his own mind” by, for instance, telling the police a secret password. Requiring such disclosure, the court noted, amounts to “extortion of information” that basically requires a person to testify against himself in violation of the Fifth Amendment.

The Virginia man will have to provide a fingerprint or go to jail for contempt of court, but will not have to have to tell the police the passcode.

Legal scholars so far have applauded this decision and the distinction it draws between physical actions and “contents of [the] mind.” But for future police investigations, the “fingerprint versus passcode” code could just make things more complicated than ever.

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