Court Rules TrueCrypt User Cannot Be Compelled To Decrypt Hard Disk

According to court documents, the man's hard drives were encrypted with a program called "TrueCrypt." As a result, the Justice Department couldn't find any files and couldn't prove that any existed on hidden portions of the drives.

The Fifth Amendment privilege isn't triggered when the government merely compels some physical act, like unlocking a safe-deposit box, the court said. But the amendment protects testimony in which a person is forced to use "the contents of his own mind" to state a fact.

"We conclude that the decryption and production would be tantamount to testimony by Doe of his knowledge of the existence and location of potentially incriminating files; of his possession, control, and access to the encrypted portions of the drives; and of his capability to decrypt the files," wrote Judge Gerald Bard Tjoflat.

Judge Tjoflat, writing for the three-judge panel, said the government was also hobbled because it could only show that the storage space on the drives could hold files that number in the millions—not that they actually do.

"It is not enough for the Government to argue that the encrypted drives are capable of storing vast amounts of data, some of which may be incriminating," the judge wrote. "Just as a vault is capable of storing mountains of incriminating documents, that alone does not mean that it contains incriminating documents, or anything at all."