Filibuster in the United States Senate

A filibuster is a tactic used in the United States Senate to delay or block a vote on a measure by preventing debate on it from ending. The Senate's rules place few restrictions on debate. In general, if no other senator is speaking, a senator who seeks recognition is entitled to speak for as long as they wish. Only when debate concludes, whether naturally or using cloture, can the measure be put to a vote.

Rule XXII of the Standing Rules of the United States Senate allows the Senate to vote to limit debate by invoking cloture on the pending question. In most cases this requires a majority of three-fifths of the senators duly chosen and sworn (60 votes if there is no more than one vacancy), so a minority of senators can block a measure, even if it has the support of a simple majority.

Even once cloture has been invoked, in most cases debate can continue for a further 30 hours, and most major bills are subject to two or three filibusters before the Senate can vote on passage. Even bills supported by 60 or more senators (as well as nominations) may therefore be delayed by a filibuster. A filibuster can also be conducted through the use of other delay tactics, such as proposing amendments or making motions.

Throughout the Senate's history, senators have frequently made efforts to curtail the use of the Senate's filibuster. Notably, in 2013 and 2017, the Senate used the nuclear option to set a series of precedents that reduced the threshold for cloture on nominations to a simple majority. Since then, nominations can be confirmed without the support of 60 senators, though they may nonetheless be delayed by a filibuster. A number of rulemaking statutes have been enacted to limit the scope of the filibuster by imposing an automatic time limit on Senate debate of certain questions. These include the Congressional Budget Act of 1974 (which created the budget reconciliation process), the Congressional Review Act and the District of Columbia Home Rule Act. Since debate on such measures ends without cloture being invoked, they are not subject to the 60-vote threshold.

Only five supermajority requirements were explicitly included in the original United States Constitution, including conviction on impeachment (two-thirds of senators present), agreeing to a resolution of advice and consent to ratification of a treaty (two-thirds of senators present), expelling a member of Congress (two-thirds of members voting in the house in question), overriding presidential vetoes (two-thirds of members voting of both houses), and proposing constitutional amendments (two-thirds of members voting of both houses). Through negative textual implication, the Constitution also gives a simple majority the power to set procedural rules.

In Federalist No. 22, Alexander Hamilton described supermajority requirements as being one of the main problems with the previous Articles of Confederation, and identified several evils which would result from such a requirement:

Originally, the Senate's rules did not provide for a procedure for the Senate to vote to end debate on a question so that it could be voted on, which opened the door to filibusters. Indeed, a filibuster took place at the very first session of the Senate. On September 22, 1789, Senator William Maclay wrote in his diary that the "design of the Virginians [...] was to talk away the time, so that we could not get the bill passed."

Although between 1789 and 1806 the Senate's rules provided for a motion for the previous question, this motion was itself debatable, so its effectiveness as a cloture mechanism was limited. Rather, it was used by the Senate to reverse its decision to consider a measure, much like today's motion to postpone. Beginning in 1811, the House of Representatives set a series of precedents to make the previous question a way of limiting debate. Throughout the 19th century, some senators unsuccessfully attempted to introduce this version of the previous question into the Senate's rules.