A new ruling by the U.S. District Court for the Northern District of California prohibits police from forcing people to unlock a mobile phone with their face, iris, or fingerprint data. The ruling was delivered in response to a search warrant request that sought biometric access to unlock all devices at a residence in Oakland. Judge Kandis Westmore denied the request, stating that biometric features were equal to a password and that they also enjoyed the same protections:

The court finds that the government's request runs afoul of the Fourth and Fifth Amendments, and the search warrant application must be denied. Today's mobile phones are not comparable to other storage equipment, be it physical or digital, and are entitled to greater privacy protection.

The Fourth Amendment states that have people have the right to be secure in their houses against unreasonable searches and seizures, while the Fifth Amendment protects against self-incrimination. From the ruling:

If a person cannot be compelled to provide a passcode because it is a testimonial communication, a person cannot be compelled to provide one's finger, thumb, iris, face, or other biometric feature to unlock that same device.

The undersigned finds that a biometric feature is analogous to the 20 nonverbal, physiological responses elicited during a polygraph test, which are used to determine guilt or innocence, and are considered testimonial.

As noted by Forbes, the ruling is a landmark decision for privacy advocates, but it remains to be seen if the District Court's verdict will be upheld in the higher courts.