Recent interest in possible changes to Senate procedural rules, and the potential difficulty of accomplishing them, has fostered renewed discussion about the procedures under which the Senate could consider such changes. Current public discussions have often described some features of these procedures in incomplete, misleading, or even inaccurate ways. This report discusses the procedural rules that govern how the Senate may consider changes in those procedural rules themselves, with emphasis on complications that may arise when proposed changes are controversial, on ways of addressing those complications, and on special considerations bearing on action at the start of a new Congress. Most of the recent interest in Senate Rules has focused on the "cloture rule" (Rule XXII paragraph 2), which permits the Senate to restrict the time for considering an item of business, and other rules that affect possible filibusters. "Filibuster" is not a formal designation for any specific procedure provided for by Senate rules; rather, it is a term colloquially used to refer to attempts to prevent or delay favorable Senate action on an item of business through dilatory or obstructive actions on the Senate floor. Historically, extended debate has been thought of as the chief means of conducting a filibuster, but other procedural actions permitted by Senate rules may also be used for the purpose. Increasingly in recent years, the term "filibustering" has also been used more loosely to refer to explicit or implicit threats to engage in dilatory action of any kind, and even to threats to block a request for unanimous consent to take up an item of business. A central issue in recent discussions has been that proposals to change Senate rules in ways that would restrict filibusters are, potentially, themselves subject to filibusters conducted consistent with the rules already in effect. This report, accordingly, focuses on the procedural mechanisms by which the Senate might accomplish a change in its rules. It does not address the content of recent proposals to change the cloture rule or associated procedures. Nor does it elaborate on the specific features of Senate rules that may affect filibustering, or how these rules may be used for filibustering purposes, except as these rules bear on the consideration of proposals to change Senate rules. The Constitution gives each house of Congress plenary power over its own rules. For changes in its code of Standing Rules, the Senate has typically exercised this power through adoption of a Senate Resolution (S.Res.). This form of measure, called a "simple resolution," is constitutionally appropriate for this purpose because it requires adoption only in the chamber where it originates, with no participation by the other chamber or the President. Largely by adopting simple resolutions in the exercise of its constitutional rulemaking power, the Senate has, at various points throughout its history, adopted, amended, and recodified its body of Standing Rules. In addition to its Standing Rules, the Senate also makes use of several other forms of procedural regulation, each of which is associated with its own typical means of adoption. (1) Those st anding orders of the Senate that continue in effect unless altered or abolished have also usually been established by the adoption of simple resolutions. Many of these have procedural effects. (2) Other s tanding orders , effective only for the duration of the Congress in which they are adopted, are typically established, and renewed in each successive Congress, by unanimous consent when the Congress first convenes. (3) Some special procedures governing measures of specific kinds, known as expedited procedures , are contained in provisions of statute, which are nevertheless understood as having been enacted pursuant to the constitutional rulemaking power of the chamber to which they apply. (4) Finally, procedural precedents interpreting the import in practice of all these forms of procedural regulation are established by rulings of the chair and votes by the Senate on appeals from such rulings. The present report, however, begins from the presumption that proposed procedural changes are sought in the form of a simple resolution amending the Standing Rules of the Senate. Several elements of the rules governing proceedings on a resolution to amend the Standing Rules of the Senate are especially important in determining how the Senate can consider such a resolution when it is controversial: (1) the Senate can adopt the resolution by a simple majority vote; (2) a supermajority vote may be needed in order to limit the time for consideration and ensure that the Senate can reach the point of voting on the resolution; (3) if this supermajority vote to limit consideration is adopted, amendments to the resolution will be limited to those that are germane and have been filed in advance; (4) a supermajority vote also may be required to limit the time for consideration of a motion to take up the resolution; and (5) in practice, the resolution could become available for consideration at all only if it had either been reported from committee or the order of business for its consideration was reached in a "morning hour." In most respects, the Senate considers simple resolutions changing the Standing Rules under the same procedures applicable to any other simple resolutions, or, indeed, measures of any form. Specifically, to begin with, the Senate can, in general, agree to any measure, including a simple resolution, by a majority of Senators voting, a quorum being present (standardly known as a "simple majority"). Under the Constitution, a quorum is a majority of all Senators. This requirement for a simple majority applies to all votes in the Senate, except as otherwise provided either by the Constitution or by any other procedural regulation of the Senate. Some have argued that the Senate has no authority to establish requirements for a supermajority vote in addition to those specified in the Constitution, but the Senate has, in practice, regarded its constitutional rulemaking power as extending to the power to establish additional supermajority requirements. Proponents of change, nevertheless, might contend that the Senate could not constitutionally require a standard higher than a simple majority for the adoption of rules. Any such higher threshold could be deemed to conflict with the constitutional grant of rulemaking power to the Senate, on grounds that, unless otherwise specified, the act of a majority of a quorum is the act of the body. In fact, the Senate has often changed its Standing Rules with the support of less than a supermajority (and even by voice vote). On December 14, 1982 (97 th Congress), for example, the Senate adopted S.Res. 512 , repealing Senate Rule XXXVI, relating to limitations on outside earned income and honoraria, by a vote of 54 to 38. Among the conditions that apply to the consideration of resolutions to change the Standing Rules, three become salient especially if the proposed change is controversial. First, like any other measure under the general Rules of the Senate, a resolution to change Senate Rules is debatable. When a question is debatable, Senate Rules place no general, overall limits on how long it can be considered or how long individual Senators can hold the floor in debate. The Senate can agree to limit the time for considering a matter by unanimous consent, but in the absence of such consent, the only mechanism provided by Senate Rules for imposing such limits is the motion for cloture (Rule XXII, paragraph 2). If the Senate votes for cloture on any debatable question, further consideration of the question is limited to 30 additional hours, after which a final vote on that question would occur. Second, also as with any other measure, when a resolution to change Senate rules is under consideration, the Senate may amend it. When a measure is amendable, Senate Rules impose no general restrictions on the subject matter of amendments that may be offered; the Senate may impose such restrictions only by unanimous consent or through cloture. Under cloture, amendments may be considered only if they are germane to the matter on which cloture was invoked and were filed at the desk by a specified deadline in advance of the cloture vote. Invoking cloture requires a supermajority vote. Senate Rules provide no means by which a simple majority can vote to bring consideration of a matter to a close or limit the amendment process. Even if a specific matter commands the support of a numerical majority of Senators, a minority of Senators may be able to prevent the Senate—either permanently or temporarily—from agreeing to the proposition by filibustering in order to forestall the Senate from ever reaching the point where a vote on the underlying question can occur. For most matters, however, invoking cloture requires three-fifths of the full membership of the Senate (60 votes, if there is no more than one vacancy). For changes in the Standing Rules, cloture can be invoked only by vote of two-thirds of Senators voting, with a quorum present. (This majority is now often referred to as "67 votes," implicitly assuming that all Senators are present and voting; if not all Senators vote, however, the votes required will be fewer, because the requirement is based on the total number voting.) For these reasons, the frequent recent assertion that a supermajority is required to amend the Rules of the Senate is imprecise. A precise statement would reflect this understanding: in cases in which opponents are willing to carry on a filibuster , it can become necessary to obtain supermajority support (by two-thirds of Senators present and voting) in order to bring the Senate to the point at which it can vote on a proposal to amend Senate Rules. An ordinary simple majority of Senators voting can then adopt the proposal itself. Other obstacles to a rules change resolution can arise in the process of taking it up for consideration, and even in the process by which it becomes available for consideration in the first place. The Senate can normally take up any measure for consideration in only two ways: by unanimous consent or by agreeing to a motion to proceed to consider. For controversial rules changes, unanimous consent could presumably not be obtained, and a motion to proceed would be necessary. A simple majority can adopt a motion to proceed, but a motion to proceed to consider a proposal to change Standing Rules is always debatable, and therefore can itself be filibustered.