The issue of forcing accused to provide hard disk encryption passwords is a pretty interesting topic these years. I just read today over on the H about how, in certain situations, password divulgence could be protected by our Fifth Amendment (protection against self-incriminating testimony). Definitely interesting.
I’m no lawyer, but there are plenty of fun issues. For instance, what if I don’t know the password but is kept on a keyfob? Does this fall into key-and-safe issues? What about a combination safe where the combination is in your head? (Though, granted, I bet *someone* can get into that safe…) Or coded documents? Law is a greatly interesting field, but I’m also glad I didn’t go down that road of study back in the day!