 The Speech or Debate Clause of Article One of the United States Constitution provides that : " [ F ] or any Speech or Debate in either House , [ Senators or Representatives ] shall not be questioned in any other Place . " United States v. Johnson ( 1966 ) was the first case in which the Supreme Court held that the Clause barred a corruption prosecution . Specifically , the Court held that a floor speech by a Congressperson could not be admitted as evidence in a prosecution under 18 U.S.C. § 281 ( the federal conflict @-@ of @-@ interest statute ) or § 371 ( conspiracy to defraud the United States ) to show the motivation for the introduction of a private bill . Representative Thomas Francis Johnson had agreed to make a speech in the House and intercede with the Department of Justice on behalf of a savings and loan association in exchange for a campaign contribution and legal fees . 
