While in most countries suspects cannot be forced to give up their passwords in order to give law enforcement access to data that could be used to indict themselves, it appears to be perfectly legal to force people to use biometric data to unlock said devices, Appleinsider reports
In a select number of cases, authorities have been able to compel courts to force criminal suspects to unlock their Touch ID-equipped iPhone using their fingerprint. That security bypass is likely to continue, legal experts say, because capturing someone’s fingerprint is a well-established practice in investigations.
So it appears that a fingerprint is doubly a bad choice for biometric device protection. Also, no phone so far has options to define a distress finger which can be used instead of the regular unlock finger, and which would destroy the data on the device instead of unlocking the device.