The Senate is governed by the Constitution, a set of standing rules, precedents established in the course of the legislative process, and special rules of procedure adopted by statute for particular types of legislation. These rules determine how bills and resolutions are moved towards passage, the structure of Senate committees, how debate proceeds on the chamber floor, and how members cast votes. The Senate adopted its first set of rules shortly after achieving a quorum in April 1789, borrowing heavily from the rules that had governed the Continental Congress and the Constitutional Convention. The Senate has added new rules gradually over time and revised the collection of rules only six times throughout its history.

Some key rules that govern lawmaking in the Senate include:

• President pro tempore: In the absence of the Vice President, the Senate shall choose a President pro tempore, who shall hold the office until the Vice President shall return.

• Suspension of rules: No motion to suspend, modify, or amend any rule, or any part thereof, shall be in order, except on one days notice in writing, specifying precisely the rule or part proposed to be suspended, modified, or amended, and the purpose thereof. Any rule may be suspended without notice by the unanimous consent of the Senate, except as otherwise provided by the rules.

• Continuation of rules: The rules of the Senate shall continue from one Congress to the next Congress unless they are changed as provided in these rules.

• Presiding officer: If any Senator, in speaking or otherwise, in the opinion of the Presiding Officer transgress the rules of the Senate, the Presiding Officer shall, either on his own motion or at the request of any other Senator, call him to order; and when a Senator shall be called to order he shall take his seat, and may not proceed without leave of the Senate, which, if granted, shall be upon motion that he be allowed to proceed in order, which motion shall be determined without debate.

• Debate: Notwithstanding the provisions of rule II or rule IV or any other rule of the Senate, at any time a motion signed by sixteen Senators, to bring to a close the debate upon any measure, motion, other matter pending before the Senate, or the unfinished business, is presented to the Senate, the Presiding Officer, or ... .

The Senate also has several powers to itself, including consenting to the ratification of treaties by a two-thirds supermajority vote and confirming the appointments of the President by a majority vote.