TL;DR
- Strings in the latest Android 15 beta suggest the OS can automatically delete biometrics that aren’t working well.
- Android will delete your face or fingerprint unlock when they aren’t working well and then prompt you to set them up again.
- We don’t know how the OS determines when a biometric isn’t working well or if this feature is even live yet in the latest Android 15 beta, though.
The legal precedents that have been set in this area basically boil down to this: if the police could unlock your phone while you were unconscious (e.g. by placing your finger on it or pointing it at your face) then they are allowed to do so.
You cannot be legally compelled to reveal your password or unlock a device with your password. Obviously you could be forced anyway, but evidence collected this way would be inadmissable in court.