Quorum

A quorum is the minimum attendance a body needs to legally transact business. Article I, Section 5 of the Constitution says that a majority of each house of Congress constitutes a quorum to do business, and that a smaller number may adjourn from day to day and compel absent members to attend.

In practice both chambers usually operate with only a few members on the floor, assuming a quorum is present unless someone objects. Any member can suggest the absence of a quorum, which prompts a quorum call. In the Senate, a quorum call is often used to pause proceedings while negotiations proceed, then ended by unanimous consent. In the House, a call might force members to come to the chamber, and the House has used a "Committee of the Whole" with a lower quorum of 100.

Quorum rules can be used for obstruction. In 1890 Speaker Thomas Reed ended the practice of "disappearing quorums," in which members present but silent denied a quorum. Senate Democrats and Republicans in state legislatures have fled to deny quorum, forcing delays. Committees have their own quorum rules for reporting bills. Quorum matters for any procedure that requires votes, such as a cloture motion.