Ruling: Thumbprint scan is like a “blood draw or fingerprint taken at booking.”
Case file: https://cdn.ca9.uscourts.gov/datastore/opinions/2024/04/17/22-50262.pdf
I wish there were a nice quick way to do lockdown on an Android phone. Right now you have to hold down the power button and tap the lockdown button on screen. Which requires you to pull out your phone and is completely obvious.
Shoot, even a time based lockdown, so like if you don’t use biometrics in the last hour or whatever, then you must use your passphrase. Or any other number of logic conditions like location, wifi connect, finger used…
I think Apple gets this a little bit more right. A hold of power and volume up locks it and requires the pin to unlock.
Android has ROMs that have stronger features, but basic Android is lacking in this area.
E.g. CalyxOS allows you to put the phone in “Before First Unlock” mode. In which even if extracted only has system data, not user data. GrapheneOS uses even stronger protections, it lock downs the whole kernel.
This isn’t the intended purpose for this app, but it can sorta work for your needs.
https://play.google.com/store/apps/details?id=vikesh.dass.lockmeout
You can set up the thing to lock on a schedule for one minute. If you don’t mind being locked out for a minute occasionally while you’re using your phone, it effectively means that if enough time passes your phone will have locked and you’ll need to use your passphrase.
Edit: anyway the existence of this function means it’s possible to write an app that does what you want.