Apple’s Emergency SOS feature in iOS 11 can also let you temporarily disable TouchID. Emergency SOS was introduced in watchOS 3, and added to the iOS 11 beta in July (Emergency SOS setup instructions). But it turns out Emergency SOS can also be used to quickly disable Touch ID (via Cult of Mac).
Why Disabling TouchID is Good
There are any number of reasons when a user might want to disable Touch ID, including those times when your device may be subject to a search. Courts have ruled that fingerprint unlocks can be compelled (forced), but have been more friendly to the idea that your passcode can’t be compelled.
Someone might be interested in keeping a criminal from using your fingerprint to force your device open, too.
iOS has long required the passcode for unlocking a device after a reboot. But that can take time and attention.
Here’s where the new “panic button” comes in. When you press the power button five times to bring up Emergency SOS, it also automatically makes you re-enter your passcode again, even if you tap the cancel button. Of course, that won’t stop the police from getting a search warrant if they really want to get inside your iPhone, but that is part of the lawful process anyway.