In the United States v. Mitchell case of 1943, the Supreme Court ruled that a member of Congress could be prosecuted for accepting bribes without violating their constitutional privilege from arrest during sessions of Congress. The court held that this protection only applied to arrests in civil suits and did not extend to criminal charges such as bribery. This decision came about after Senator Joseph F. Guffey was indicted on charges of conspiracy and bribery while serving as a U.S senator from Pennsylvania, which he argued violated his immunity under Article I, Section 6 (the Speech or Debate Clause) of the Constitution. However, Justice Felix Frankfurter rejected this argument stating that members are protected by parliamentary immunity only when carrying out legislative duties but not when they engage in criminal activities.

In the dissenting opinion for United States v. Mitchell, Justice Frank Murphy argued that the majority's decision to uphold a conviction based on evidence obtained through wiretapping was a violation of privacy rights and due process under the Fourth Amendment. He contended that allowing such evidence would open up dangerous possibilities for government intrusion into private lives without proper checks or balances. Furthermore, he expressed concern over how this ruling could potentially undermine public trust in law enforcement agencies by giving them unchecked power to invade personal privacy with impunity. In his view, it was crucial to maintain strict boundaries between lawful investigation methods and those which infringe upon individual liberties - even if such measures might occasionally impede criminal investigations.