Felix Frankfurter,
Ullmann v. United States — Opinion of the Court
“ Assuming that the statutory requirements are met, does the Act give the district judge discretion to deny an application for an order requiring a witness to answer relevant questions put by the grand jury, and, if so, is the court thereby required to exercise a function that is not an exercise of 'judicial Power'? Did Congress provide immunity from state prosecution for crime, and, if so, is it empowered to do so? Does the Fifth Amendment prohibit compulsion of what would otherwise be self-incriminating testimony no matter what the scope of the immunity statute? ”
