Yes, but only if they know there to be an encrypted partition. Because all encrypted data passes a Chi^2 randomness test you cannot (really cannot) distinguish between empty space on an encrypted partition and a different encrypted partition inside an encrypted partition.

So when they find a drive that passes the Chi^2 randomness test they know there has to be encrypted data on there, so you give them the key and they decrypt the outer ring (which contains nothing important). At that point they're stuck. They suspect there's got to be more to it, but they can't point to anything and say "decrypt this!", because there isn't anything to point to. So technically, they have to let you go. Or so I heard.

I disagree. See my post here: http://news.ycombinator.com/item?id=1296381

Isn't that covered by the 5th Amendment (not 100% sure, I'm not American)?

The 5th Amendment says that you can't be compelled to incriminate yourself, but I don't think that covers everything. If you have a safe in your house and the police have a search warrant for the contents of the safe, I think you are legally required to turn over the combination or key.

I remember hearing about this being used as a justification by a judge in a case relating to encryption. It's just sad that most cases involving encryption / computer crimes are related to child porn charges so people are more worried about punishing the person than they are about protecting the rights of everyone that is brought into the court system.

Oh I see, thanks. I didn't realize this kind of jurisprudence was linked to the child porn issues. Obviously that's a commendable reason to add exceptions to the 5th amendment.