Oh god.
It is evidence. Just like the example of the safe brought up early on, if the court has a warrant for the INFORMATION ON THE HD, they have the right to ask for it to be decrypted.
They do not have the right to just go around asking for things with no reason and no proof.
If they open the drive up (figuratively speaking) and find out she was running guns from Mexico, that is akin to opening the safe and finding paper documents saying the same thing. It does not MATTER if that was not related to the case, it is another crime that should be tried and punished on discovery.
Now, OTOH, if they found love letters in there to someone she was having an affair with that she said, in testimony, that she wasn't... well, then that is entrapment. So long as that person had nothing to do with the original charges or with any other criminal act, lying about (him) to save face should not be brought up as a crime (ala Clinton/Lewinski).
Whatevah.