FYI for iPhone users if you run into the Fuzz and you need to lock it out of biometrics, hit the lock button five times. This will start the emergency call count down but once canceled the iPhone can only be opened via passcode.
Caveat, you need to have the five press to call turned on in Settings>Emergency SOS>Call with 5 Button presses
On my Android I can scan the wrong finger a few times and it'll ask for my pin instead. I'm pretty sure rebooting would do the same but I'm too lazy to try that right now.
However, please make sure you try this yourself for your specific phone and Android version before relying on it.
Reboot has forced PIN/Pass for I think the entirety of Androids existence, but if not then for sure long enough that the phones that didn't don't work anymore as phones.
Rebooted android requires pin/pass only because you are essentially un-encrypting the phone. So if you use android and get in a mess with the police, shut down your phone immediately. It's been this way for a long time, but it's been far too long since 1.0-4.0 that I can't remember.
Pattern unlock is effectively the same as a pin, just without numbers. You can use the pattern unlock without the PIN code. But fingerprint unlock is a secondary unlock type on top of the primary one which is a PIN code. And no, they haven't changed it, if you reboot the phone, a pin code is required first in order for it to boot up.
On my Android I can scan the wrong finger a few times and it'll ask for my pin instead.
Be careful. If they've ordered you to use your fingerprint to unlock the phone, and you "accidentally" do it wrong five times in a row to cause the device to lock, that may be considered disobeying an order.
You would want to lock the phone down before they've ordered you to do this.
idk maybe its just my phone (I'm on graphene os, a privacy and security focused ROM) but I have an option for "lockdown mode" which disables biometrics
You can also just hold the power and volume up buttons. You don’t actually have to swipe to power off the phone. Just holding those buttons long enough for the “Swipe to power off” to appear on screen will also lock out biometrics and force a PIN.
For Android there's a literal "lockdown mode" button on the lock screen that does this, if you push it you can only use pattern or PIN for the next unlock.
If you haven't locked the device down by the time they have instructed you to unlock it, doing then might be considered obstruction, but until they compel you to do it, you can do whatever you like with the phone.
As for destruction of evidence, it certainly wouldn't be that, but even if it could be, it would kind of depend on them proving intent because you're not under arrest yet or charged with anything. They would have to prove that you were aware of an impending investigation when you made the choice to dispose of evidence.