From cryptome:

A federal judge in Vermont has ruled that prosecutors can't force a criminal defendant accused of having illegal images on his hard drive to divulge his PGP (Pretty Good Privacy) passphrase. U.S. Magistrate Judge Jerome Niedermeier ruled that a man charged with transporting child pornography on his laptop across the Canadian border has a Fifth Amendment right not to turn over the passphrase to prosecutors. The Fifth Amendment protects the right to avoid self-incrimination.