https://www.techdirt.com/articles/20190114/15001941387/federal-judge-says-compelling-people-to-unlock-phones-with-their-fingerprints-faces-violates-5th-amendment.shtml

The advent of biometric "passcodes" -- fingerprints and facial recognition -- appear to be leaving those who choose these methods with fewer Fifth Amendment protections. A handful of courts have ruled fingerprints and faces aren't "testimony." Much as officers can collect fingerprints and mugshots without a warrant following an arrest, they can also apply fingers and faces to locked phones to get to the data inside.

But it's not as simple as some court decisions make it appear. Even passwords can be considered testimonial, as they may indicate ownership of a locked device or compel production of evidence to be used against the device's owner. The passcode argument has gone both ways in court, which usually comes down to the individual judge's definition of "foregone conclusion." Does the foregone conclusion refer to the device's ownership or the evidence contained in it? The latter is harder to prove, and raising the burden of proof to this level tends to result in courts finding the compelled production of passwords to be a Fifth Amendment violation.