disclosures for the purpose of aiding the prosecution of pending suits," the Court declared that the authority "to require pertinent disclosures in aid of its own constitutional power is not abridged because the information sought to be elicited may also be of use in such suits."[104] JUDICIAL FUNCTIONS 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.[105] The decision in Barry _v._ United States ex rel. Cunningham[106] sanctioned the exercise of a similar power in investigating a Senatorial election. SANCTIONS OF THE INVESTIGATORY POWER Contempt Explicit judicial recognition of the right of either House of Congress to commit for contempt a witness who ignores its summons or refuses to answer its inquiries dates from McGrain _v._ Daugherty. But the principle there applied had its roots in an early case, Anderson _v._ Dunn,[107] which affirmed in broad terms the right of either branch of the legislature to attach and punish a person other than a member for contempt of its authority--in that case an attempt to bribe one of its members. The right to punish a contumacious witness was conceded in Marshall _v._ Gordon,[108] although the Court there held that the implied power to deal with contempt did not extend to the arrest of a person who published matter defamatory of the House. Both Anderson _v._ Dunn and Marshall _v._ Gordon emphasized that the power to punish for contempt rests upon the right of self-preservation; that is, in the words of Chief Justice White, "the right to prevent acts which in and of themselves inherently obstruct or prevent the discharge of legislative duty or the refusal to do that which there is inherent legislative power to compel in order that legislative functions may be performed."[109] Whence it was argued, in Jurney _v._ MacCracken[110] that the Senate had no power to punish a witness who, having been commanded to produce papers, destroyed them after service of the subpoena, because the "power to punish for contempt may never be exerted, in the case of a private citizen, solely _qua_ punishment. * * * the power to punish ceases as soon as the obstruction has been removed, or its removal has become impossible; * * *" The Court confirmed the power to punish for a past contempt as an appropriate means for vindicating "the established and essential privilege of requiring the production of evidence."[111] Criminal Prosecutions