The Fifth Amendment precludes that. > No person shall...be compelled in any criminal case to be a witness against himself Courts have previously upheld passwo

The Fifth Amendment precludes that. > No person shall...be compelled in any criminal case to be a witness against himself Courts have previously upheld passwords as self-implicating information, which you cannot be constitutionally compelled to provide. > in In re Boucher (2009), the US District Court of Vermont ruled that the Fifth Amendment might protect a defendant from having to reveal an encryption password, or even the existence of one, if the production of that password could be deemed a self-incriminating "act" under the Fifth Amendment. http://en.wikipedia.org/wiki/In_re_Boucher http://en.wikipedia.org/wiki/In_re_Boucher Boucher ended up having to unlock the hard drive, because he had previously unlocked the drive for border agents. Had he refused, the court likely would have held that he could not be compelled to produce the password or the hard drive contents. A warrant gives law enforcement the right to gather evidence, but doesn't compel you to provide it. If you won't provide it, they are authorized to take it by force. In the case of encryption, they don't have enough (legal) force to take it. Therefore, they are entirely dependent on the accused cooperating to gather that information, but the accused cannot be compelled to cooperate under the Fifth. This is scary for them, because it means that they can't legally compel you to give up the information, and they can't gain access to it by force. A wholly uncooperative defendant is effectively unassailable.