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