Article One of the United States Constitution
Section Five states that a majority of each House constitutes a quorum to do business; a smaller number may adjourn the House or compel the attendance of absent members. In practice, the quorum requirement is all but ignored. A quorum is assumed to be present unless a quorum call, requested by a member, proves otherwise. Rarely do members ask for quorum calls to demonstrate the absence of a quorum; more often, they use the quorum call as a delaying tactic.