by John Marshall Harlan, Emspak v. United States — Dissent
“ The answer to almost any question a witness is asked could be regarded as being useful as evidence, or as furnishing a lead to evidence, in support of some conceivable criminal charge against the person to whom the question is addressed. But unlike a defendant in a criminal case, a witness in a grand jury or other judicial or legislative proceeding has never been allowed, by claiming his privilege, to refuse to answer any questions at all. ”
