Proposals to limit Senate debate are as old as the Senate itself. Over the 224-year history of the body, numerous procedures have been proposed to allow the Senate to end discussion and act. The most important debate-limiting procedure enacted was the adoption in 1917 of the "cloture rule," codified in paragraph 2 of Senate Rule XXII. Under the current version of this rule, a process for ending debate on a pending measure or matter may be set in motion by a supermajority vote of the Senate. Since the Senate's adoption of the cloture rule in 1917, proposals have been advanced to repeal or amend it in almost every session of Congress. At times, Senators of both political parties have debated the merits of the Senate's tradition of free and unlimited debate. These debates have occurred at different times and under different sets of circumstances as Senators attempted, for example, to prevent filibusters of civil rights measures, pass consumer protection legislation, or secure the confirmation of judicial or executive branch nominations. Debates on the cloture rule have frequently focused on whether the Senate must consider amendments to it under the body's existing rules, including Rule XXII itself. This argument rests on the principle that the Senate is a "continuing body," and relatedly, that its rules stay in force from one Congress to the next. A contrary argument contends that this principle has the effect of "entrenching" the existing rules against change, a situation which amounts to an unconstitutional limit on the power of the body to set the terms of its own operation. To overcome these difficulties, Senators attempting to change Rule XXII have employed various procedural tactics, including seeking to invoke cloture by majority vote, seeking opinions by the Vice President acting as presiding officer that the cloture rule itself is unconstitutional, and arguing that the Senate's standing rules do not apply on the first day of a Congress. Although many attempts have been made to amend paragraph 2 of Rule XXII, only six amendments have been adopted since the cloture rule was enacted in 1917: those undertaken in 1949, 1959, 1975, 1976, 1979, and 1986. Each of these changes was made within the framework of the existing or "entrenched" rules of the Senate, including Rule XXII. In 1949, the cloture rule was amended to apply to all "matters," as well as measures, a change that expanded its reach to nominations, most motions to proceed to consider measures, and other motions. A decade later, in 1959, its reach was further expanded to include debate on motions to proceed to consider changes in the Senate rules themselves. The threshold for invoking cloture was lowered in 1975 from two-thirds present and voting to three-fifths of the full Senate except on proposals to amend Senate rules. In a change made in 1976, amendments filed by Senators after cloture was invoked were no longer required to be read aloud in the chamber if they were available at least 24 hours in advance. In 1979, Senators added an overall "consideration cap" to Rule XXII to prevent so-called post-cloture filibusters, which occurred when Senators continued dilatory parliamentary tactics even after cloture had been invoked. In 1986, this "consideration cap" was reduced from 100 hours to 30 hours. In its current form, which was adopted in 1986, Rule XXII provides that a cloture motion must be signed by 16 Senators and presented on the Senate floor. One hour after the Senate meets on the second calendar day of session after a cloture motion has been filed (and after a quorum has been ascertained), the presiding officer puts the question, "Is it the sense of the Senate that the debate shall be brought to a close?" The cloture motion is then subject to a mandatory yea-and-nay vote. If three-fifths of Senators—60 if there is no more than one vacancy in the body—vote for the cloture motion, the Senate must take final action on the matter on which it has invoked cloture by the end of 30 total hours of additional consideration. Invoking cloture on a proposal to amend the Senate's standing rules requires a higher threshold: approval by two-thirds of the Senators present and voting or 67 senators if there are no vacancies and all Senators vote. Once cloture has been invoked, the clotured matter remains the pending business of the Senate until it is disposed of, and no Senator may speak for more than one hour. Senators may yield all or part of their allotted hour to a floor manager or floor leader, who may then yield time to other Senators. Each floor manager and leader, however, can have no more than two hours in total yielded to him or her. As with most Senate procedures, any of these requirements may be waived or their operations altered by unanimous consent. The mandatory quorum call, for example, is almost always waived by unanimous consent. After cloture has been invoked, no dilatory amendments or motions are permitted, and all debate and amendments must be germane. Only amendments filed before the cloture vote (or still pending, if germane) may be considered, and a Senator may not call up more than two amendments until every other Senator has had an opportunity to do likewise. Printed amendments that have been available for at least 24 hours are not read when called up. Time for votes, quorum calls, and other actions is charged against the 30-hour limit on consideration. This time limit may be extended by joint leadership motion if three-fifths of all Senators vote for a non-debatable motion to do so. Senators who have not used or yielded 10 minutes of their hour are guaranteed up to 10 minutes to speak. When all time expires, the Senate immediately votes on any pending amendments and then on the underlying matter. Supporters of extended debate believe that the American system of government should safeguard certain rights of legislative minorities against the power of a majority. Further, they argue, obstruction is sometimes justified to prevent a majority from restricting the rights of a minority until a broad political consensus has developed on an issue. They note that the structure of the Senate was intended to protect the rights of smaller states, and assert that the diminishment of minority rights would undermine this intent. Defenders of extended debate also contend that, in the long run, matters that are truly in the nation's best interest have not been permanently blocked by extended debate. Likewise, the Senate's tradition of debate has protected different political parties at different times in history. The cloture rule has been in effect for nearing 100 years with little ill effect, they contend. Supporters of extended debate believe that the ability of any Senator to speak at length about virtually any topic at any time is a unique characteristic of the Senate that allows the chamber to play a vital role in the legislative process, serving to cool passions and force deliberation. Furthermore, supporters argue, this more deliberative approach was intended by the framers of the Constitution, differentiating the Senate from the House. Removed of this deliberative function, they believe the Senate would become a shadow of the larger House of Representatives, and would specifically surrender its unique role as a check on the executive branch through its role in executive business—that is, nominations and treaties. Supporters of restricting debate argue that it is undemocratic to allow a determined minority to prevent an institutional majority from working its will. They say that the current process gives too much power to the minority at the expense of the majority, contending that although the founders intended the Senate to be more deliberative than the House, they did not intend to create a chamber where the minority could stall or prevent all action. Further, they believe it undermines public accountability of a majority in its responsibilities to manage the chamber's policy agenda. In addition, extended debate by one Senator or a small group of Senators expends valuable time and money, supporters of changing debate rules argue, and brings public disrepute because the Senate cannot act in a timely fashion on important issues. Much legislation and many qualified nominations have been delayed or defeated by extended debate, they contend. Supporters of proposals to limit debate assert that their proposed changes would still provide those who oppose a bill or matter significant time to discuss the proposal, but would not allow them to block action on it if a majority of the Senate supported it. Proponents of additional debate limitations focus on the benefits of an up or down vote, regardless of the outcome. As noted above, the Senate has considered—and in some cases, adopted—changes to the cloture rule and associated procedures at various times in the past. In recent Congresses—and perhaps especially in the 112 th (2011-2012) and 111 th (2009-2010) Congresses—some Senators have expressed renewed concern over the effect of extended debate on the Senate's capacity to act efficiently. Rather than list all (sometimes overlapping) proposals introduced in recent Congresses, the discussion below groups proposals into categories based on the procedural mechanism by which the change would be effected or the overall goal of the change. The first category addressed below includes proposals that provide a non-rule-based mechanism by which the Senate could change its rules or precedents, or both, without needing to surmount the supermajority hurdle present in existing rules; specifically, these proposals hinge on a novel ruling by the Senate's presiding officer in relation to Senate rules on debate or the constitutionality thereof. The second category discussed focuses on changes to the rules that would alter the vote threshold by which cloture is invoked. A third group of proposals focuses on the time the Senate must expend in using the cloture process to end debate on a question. Fourth, the report discusses proposals to limit debate on only certain questions (e.g., on the motion to proceed, motions related to establishing a conference committee). The fifth and final category addressed includes proposals that would increase the procedural burden on those opposing an end to debate on a particular matter.