“It should be a welcome ruling from the perspective of privacy advocates like the Electronic Frontier Foundation, which decried a similar police effort in California last autumn.”

Police cannot walk into a building and order everyone inside to unlock their iPhones via fingerprint scan, an Illinois federal court has ruled.

The case arose from police efforts to disrupt a suspected child pornography ring. They sought permission to enter a premises, and to demand that its inhabitants unlock their iPhones with Touch ID, believing that incriminating evidence may be stored on such devices.

In his ruling, Judge M. David Weisman determined that the broadness of this approach violates Fourth Amendment protections against unreasonable search and seizure, and Fifth Amendment protections against self-incrimination. With respect to the former, the judge essentially suggested that police ought to have specific suspicions against particular individuals, and cannot search someone’s phone just because they happen to be on the premises, though he emphasized that it’s “the context in which fingerprints are taken, and not the fingerprints themselves,” that raises concerns. As for the Fifth Amendment, he ruled that the fingerprint scan itself can be self-incriminating, since by performing fingerprint unlock “a suspect is testifying that he or she has accessed the phone before, at a minimum, to set up the fingerprint password capabilities, and that he or she currently has some level of control over or relatively significant connection to the phone and its contents.”

It should be a welcome ruling from the perspective of privacy advocates like the Electronic Frontier Foundation, which decried a similar police effort in California last autumn. But with a recent Minnesota Court of Appeals ruling finding that a compelled fingerprint unlock is “no more testimonial than furnishing a blood sample” with respect to Fifth Amendment concerns, this is still very much a contested legal frontier.

Sources: Forbes, Ars Technica

(Originally posted on FindBiometrics)