At least with fingerprints, you can effectively destroy the "password" irreversibly before being compelled, since you can always cut off the tip of your finger and destroy it.
Sounds messed up, but it's certainly a possibility. Since the finger is not the evidence itself, I don't think this would constitute destruction of evidence, and so long as it is done before the court asks you to unlock the device, it should not result in contempt of court. However, this is all uncharted territory and IANAL.
only until it is an attached part of your body :) I can see how destroying the tip of your finger and cutting after that is ok, while in reverse would be a destruction of evidence.
Sounds messed up, but it's certainly a possibility. Since the finger is not the evidence itself, I don't think this would constitute destruction of evidence, and so long as it is done before the court asks you to unlock the device, it should not result in contempt of court. However, this is all uncharted territory and IANAL.