That depends on where you live. The 5th Amendment (or its equivalent) doesn't exist everywhere and in many countries you can be forced to incriminate yourself. We're not talking about backwards third world countries either. As the Tails dev said above, key disclosure laws exist in the UK and France. In the UK, you can get up to 2 years for not providing a password. I'm belaboring this point, because we have a lot of Brits on this forum, so its relevant to them. Now, if hidden volumes become popular, LE could assume everyone is using them. So if they find no incriminating evidence after you truthfully provide the password to the only encrypted volume on your computer, they could assume you're still hiding something. Plausible deniability becomes plausible suspicion, and grounds to keep you locked up (in the best case). If you are protected from self incrimination and key disclosure, then you don't need a hidden volume. You can just say Fuck You LE when they ask for your password. So hidden volumes are either dangerous or useless. Well, that's their argument anyway. I don't really care one way or the other.