While I agree with this ruling in terms of privacy protection and right against self-incrimination, I believe that this effectively means that, for example, all TrueCrypt containers can never be forcibly decrypted.
For example: if you have 13_year_old_girl.jpg.pgp, it could be reasonably argued that the content of the encrypted file is "known," and decryption can be forced. If, however, you have a TrueCrypt partition called "images," there is plausible deniability due to the very nature of a TrueCrypt container - so everything within would be considered protected.
It's an interesting case, with serious ramifications - for example, if a hacker stole source code and put it in a TrueCrypt container and was subsequently raided, it would be significantly harder to prosecute without incriminating evidence.
I think the premise "if they have no clue what's on my HDD, then they have no right to force me to decrypt it" is a good one. Anything else is an invitation for abuse.
It's the same with police car searches. You have the right to refuse a search, if they don't have probable cause, because even you might not know if there is something in there that could get you arrested. If that works for car searches, I think it should work just the same for encryption.
For example: if you have 13_year_old_girl.jpg.pgp, it could be reasonably argued that the content of the encrypted file is "known," and decryption can be forced. If, however, you have a TrueCrypt partition called "images," there is plausible deniability due to the very nature of a TrueCrypt container - so everything within would be considered protected.
It's an interesting case, with serious ramifications - for example, if a hacker stole source code and put it in a TrueCrypt container and was subsequently raided, it would be significantly harder to prosecute without incriminating evidence.