Article I, Section 1:
All legislative Powers herein granted shall be vested in a Congress of the United States, which shall consist of a Senate and House of Representatives.
When either House exercises a judicial function, as in judging of elections or determining whether a member should be expelled, it is clearly entitled to compel the attendance of witnesses to disclose the facts upon which its action must be based. Thus, the Court held that since a House had a right to expel a member for any offense which it deemed incompatible with his trust and duty as a member, it was entitled to investigate such conduct and to summon private individuals to give testimony concerning it. 1 The decision in Barry v. United States ex rel. Cunningham 2 sanctioned the exercise of a similar power in investigating a senatorial election.