If you initiate a wipe before approaching immigration, which swaps the whole phone contents to an encrypted backup that you physically can't decrypt without a key that (say) a friend knows. Then you would be offering immigration the device in an unaltered state between when they request it and when they receive it. Any request for an alternative pass code or whether the pass code given will alter the state of the device can be honestly answered.
I am curious if this is still obstruction - you still defeated their intent. If the law is just about intent, you can never defeat it.
I am curious if this is still obstruction - you still defeated their intent. If the law is just about intent, you can never defeat it.