The fifth amendment to the US Constitution prohibits the police from forcing you to reveal your phone's PIN or password, but the courts have ruled that the protection does not apply to a fingerprint or face unlock. Now that could change.
That's how it came to pass: An arrest warrant was filed in Oakland calling for a raid and seizure of personal property, including access to all mobile devices ̵
Forbes writer Thomas Brewster points out why this is such a significant verdict:
But in a more important part of the ruling, Judge Westmore stated that the government did not have the right to force suspects themselves to incriminate themselves by releasing their devices with their biological characteristics. Previously, courts have ruled that biometric features, unlike passcodes, are not considered "testimonials." This is because a suspect must voluntarily and verbally give up a passcode, which is not the case with biometrics. A password was therefore regarded as a testimony, but body parts were not granted, and thus not the protection of the Fifth Amendment against self-harm.
It makes sense because if passwords and PIN codes are protected, biometric locking options should not be considered any different. They are just another means for the same purpose.
However, this is probably a controversial decision that will have more impact over time.