Whenever a witness refuses, on the basis of his privilege against self-incrimination, to testify or provide other information in a proceeding before or ancillary to—

(1) a court or grand jury of the United States,

(2) an agency of the United States, or

(3) either House of Congress, a joint committee of the two Houses, or a committee or a subcommittee of either House,

(Added Pub. L. 91–452, title II, § 201(a), Oct. 15, 1970, 84 Stat. 927; amended Pub. L. 103–322, title XXXIII, § 330013(4), Sept. 13, 1994, 108 Stat. 2146.)