In the 1928 case of Barry, Sergeant-at-Arms of the United States Senate, et al. v. United States ex rel. Cunningham, the Supreme Court ruled on a dispute involving legislative immunity and separation of powers principles. The case arose when William P. Barry, as Sergeant-at-Arms for the U.S Senate, arrested Mally S. Daugherty under orders from a Senate committee investigating alleged corruption in Attorney General Harry Daugherty's office during President Harding's administration (Mally was Harry’s brother). Mally refused to testify or produce documents requested by the committee and was held in contempt and jailed by Barry. Daugherty filed for habeas corpus relief arguing that his detention violated his Fifth Amendment rights against self-incrimination since he could be criminally prosecuted based on evidence produced before Congress; also claiming that it exceeded Congressional authority because no legislation could result from such an inquiry. The Supreme Court sided with Daugherty stating that while Congress has broad investigative power necessary to legislate effectively; this does not include punishing individuals refusing cooperation unless their non-cooperation obstructs legislative functioning directly - which wasn’t proven here.

In the dissenting opinion for Barry, Sergeant-at-Arms of the United States Senate, et al. v. United States ex rel. Cunningham (1928), Justice Oliver Wendell Holmes argued that the majority's decision was a departure from established precedent and an overreach of judicial power into legislative affairs. He contended that it was not within the Court's purview to question or interfere with how Congress conducts its internal procedures or disciplines its members, as these matters are constitutionally entrusted to each House of Congress alone under Article I, Section 5 of the Constitution. Furthermore, he expressed concern about potential negative consequences on Congressional independence and functioning if courts could review such actions by Congress in future cases.