I n general, the Senate's presiding officer does not take the initiative in enforcing Senate rules and precedents. Instead, a Senator may raise a point of order if he or she believes the Senate is taking (or is about to take) an action that violates the rules. In most circumstances, the presiding officer rules on the point of order on advice of the Parliamentarian; that ruling is typically subject to an appeal on which the Senate votes (unless the appeal is tabled or withdrawn). Pursuant to Rule XX, however, in certain circumstances a point of order is not ruled on by the presiding officer but is instead submitted to the Senate for its decision. A point of order that a pending matter (a bill or amendment, for example) violates the U.S. Constitution presents one such circumstance. This report explains Senate rules, precedents, and practices in regard to these constitutional points of order, including an analysis of recent cases in which such a point of order has been raised. This report will be updated as events warrant. The process for raising a constitutional point of order against a pending question does not differ from that for raising other points of order. A Senator seeking to raise a constitutional point of order would simply address the presiding officer at a time when no one else holds the floor. The Senator might say, "Mr. President, I rise to point of order" or simply "Point of order, Mr. President" and then proceed to state and explain the way in which the pending matter violates the Constitution. Raising a constitutional point of order (or any point of order) confers no special recognition rights—unless a unanimous consent (UC) agreement has provided for it being raised, or considered as raised, at a certain time. No Senator can interrupt another Senator without his or her consent for the purposes of raising a point of order. In addition, a Senator loses the floor after he or she has raised the point of order, though the Senator could again seek recognition from the presiding officer once the point of order is submitted. A UC agreement may affect the availability of any point of order when the agreement includes language that prohibits all or certain points of order. In addition, if a UC agreement specifies that a vote on a matter would occur "at a time certain without any intervening action," it would preclude a point of order being raised. Further, if a UC agreement limits the time for debate of a matter, then the point of order can be raised against it only after the debate time has been used or yielded back—except by unanimous consent. This is because if a matter has been guaranteed—by UC—a certain amount of debate or a vote at a time certain, then a new UC agreement is required to allow a point of order before that debate is complete, since the disposition of the point of order could have the effect of making the matter fall. Under current practice and precedents relating to Rule XX, a point of order that a pending matter is unconstitutional is submitted to the Senate for decision rather than ruled upon by the presiding officer. The logic behind the relevant precedents is that while the presiding officer has authority to interpret Senate rules, he or she does not have the authority to interpret the Constitution. While the Senate, in its earliest history, similarly disposed of constitutional points of order through a vote of the body, there were some intervening periods during which practice varied. For an approximately 40-year period in the late 19 th and early 20 th centuries, these points of order were not submitted for disposition, but instead the proceedings resembled the current practice in the House of Representatives, under which Members are expected to implicitly express their opinion on the constitutionality of a measure by their vote for or against the measure itself. However, the Senate has generally followed its current practice of submitting constitutional points of order since establishing a relevant precedent in 1924. Sustaining the submitted point of order requires an affirmative vote of a majority of Senators voting, assuming a quorum is present. A point of order submitted to the Senate for decision is debatable except when the Senate is operating under cloture. Under most circumstances, accordingly, a cloture process could theoretically be used to end extended debate and force a vote on the point of order. Under some circumstances, statutory provisions may limit debate on points of order; these debate limits would apply equally to a submitted constitutional point of order. While a submitted point of order is generally subject to extended debate, it is also subject to a non-debatable motion to table. The tabling motion could be made at any time after the point of order has been raised unless the Senate had agreed by UC to provide a specific amount of time for debate on the point of order, in which case the tabling motion could not be made until the time has expired or been yielded back. Agreeing to a tabling motion requires a majority of those voting (assuming a quorum is present). If the motion is agreed to, it adversely and permanently disposes of the point of order. Thus, if a Senator makes a motion to table the point of order, a majority of Senators could dispose of the point of order by agreeing to the motion to table. This disposition would have the effect of determining the constitutional point of order not to be well taken. A unanimous consent agreement may affect the debatability of a submitted point of order. For example, if a UC agreement sets a time certain for a vote on the matter on which a point of order is contemplated, then a submitted point of order raised against that matter would be subject to debate only until that time expires. Other language in a UC agreement (e.g., that establishes a specific amount of debate time on a pending amendment and provides for another action immediately upon the disposition of that amendment) may also preclude extended debate on a constitutional point of order raised against that amendment. Constitutional points of order are not common, relative to many other points of order that are more routinely made (e.g., that an amendment violates the Congressional Budget Act or that an amendment to an appropriations bill constitutes legislation). Table 1 presents data on constitutional points of order in the Senate made since 1989 (the start of the 101 st Congress) on which the Senate voted, as identified in the Legislative Information System (LIS) and the Daily Digest . (An examination of references to constitutional points of order in the full text of the Congressional Record for the Congresses in question did not produce any additional examples.) The table does not include any constitutional points of order that were raised but then withdrawn before a Senate vote or those that may have been rendered moot because the underlying matter was withdrawn or otherwise negatively disposed of. Of the cases identified, more than half (11 of 17) were disposed of negatively, either through a direct vote on the point of order or via a successful motion to table; the remaining six points of order were sustained. Five of the six sustained points of order were in relation to an alleged violation of the Origination Clause (Article 1, Section 7, clause 1, which provides that only the House may originate revenue measures). Of the 11 points of order that were not well taken, 10 were raised in relation to other constitutional provisions. The table makes clear that constitutional points of order raised in the 106 th and 107 th Congresses were raised exclusively on the grounds that the pending matter would violate the Origination Clause. In the most recent Congresses (111 th and 113 th ) in which constitutional points of order were raised, however, they were raised only in relation to other provisions of the Constitution. This dominance of points of order on the grounds of other (non-Origination Clause) constitutional provisions is also evident in the Congresses spanning the 1990s. This recent ebb and flow in the constitutional grounds on which such points of order are raised is similar to the historical variation that characterizes previous periods. While the Origination Clause was the primary constitutional provision invoked prior to the 1960s, other constitutional provisions were referenced with almost equal frequency in the subsequent decades. For example, from the 1960s to 1980s, points of order were raised on constitutional grounds such as the ability of the Senate to make its own rules, the process for proposing constitutional amendments, representation and apportionment issues, the line item veto, and the Equal Protection Clause. As noted in the table above, the two most recent decades included points of order raised in relation to the First Amendment, the Due Process Clause, questions of congressional apportionment and representation, and the powers afforded to Congress (and reserved to the states), among others.