A password is considered (by courts) to be testimony. Face, gesture or fingerprints are considered things like keys which you can be forced/compelled to turn over when commanded by law enforcement. Therefore, only passwords, which will require a court order to unlock, are secure enough for now.
> A password is considered (by courts) to be testimony
For now. It doesn't seem like an especially natural fit. Regardless of the merits of being able to compelled to turn over your password, relying on labored interpretation of laws is not a good idea: 14th amendment was always a very shaky basis for abortion rights, as the 2nd is a very shaky one for personal gun rights.
