The Constitution requires a simple majority to pass legislation, but the Senate's rules allow debate to continue until three fifths of the full Senate votes to end it. Because nearly every significant bill now faces that hurdle, the practical rule in the modern Senate is that most legislation needs 60 votes. No other feature of Congress does more to shape what can pass.
This guide explains how filibusters and cloture work, traces their history, lists the major exceptions, explains the nuclear option, and lays out the arguments for and against the rule.
Congress has written exceptions into law for certain measures. Budget reconciliation bills, which can change taxes, spending, and the debt limit, need only a simple majority, subject to the Byrd rule barring unrelated provisions. Resolutions under the Congressional Review Act, trade agreements under fast-track authority, resolutions ending national emergencies, and some war powers resolutions also have expedited procedures. Major laws passed through reconciliation include the tax laws of 2017 and 2025.
Defenders argue that the filibuster forces the majority to build broad coalitions, protects the rights of the minority party and smaller states, and prevents sweeping policy swings each time Senate control changes. Critics argue that it lets senators representing a minority of Americans block popular bills, encourages reliance on executive orders and reconciliation, and worsens gridlock and shutdown standoffs. Proposals include abolishing it, restoring a requirement to hold the floor by talking, lowering the threshold over time, or carving out specific subjects. Positions on the filibuster often shift depending on which party holds the majority.
The Senate dropped its previous question motion in 1806 on the advice that it was rarely used, leaving no way to end debate. By the mid-nineteenth century senators had discovered the filibuster. A cloture rule was adopted in 1917, requiring two thirds of senators voting. For decades filibusters were rare and were used most notably by Southern senators against civil rights bills, including a record one-person speech of more than 24 hours in 1957 and a weeks-long filibuster broken in 1964. In 1975 the threshold was lowered to three fifths of the full Senate, or 60 votes.
The majority leader files a cloture motion signed by 16 senators. Two days later the Senate votes, and if 60 senators agree, debate is limited to 30 more hours. Since the 1970s the Senate has used a two-track system that lets other business continue during a filibuster, which made silent filibusters easy and the 60-vote expectation routine. Cloture votes, once rare, now number in the hundreds per Congress. Talking filibusters still occur as protests, and in April 2025 a senator spoke for more than 25 hours, setting a new record.
Senate rules let senators speak as long as they wish and offer amendments freely unless debate is limited by unanimous consent or cloture. A filibuster uses those rights to prevent a final vote. Senators can also place holds, informal notices that they will object to taking up a measure, which often function as a threatened filibuster. Because floor time is scarce, the mere threat usually forces the majority leader to seek 60 votes or move on.
Changing Senate rules formally requires cloture by two thirds of senators voting, but a majority can instead set a new precedent by overruling the presiding officer, a move known as the nuclear option. Democrats used it in 2013 to end filibusters on executive nominations and lower-court judges, Republicans extended it to Supreme Court nominees in 2017 and shortened post-cloture debate in 2019, and in September 2025 Republicans used it to allow groups of sub-cabinet nominees to be confirmed together. The legislative filibuster has so far survived proposals to eliminate it, including in 2022 and during the fall 2025 shutdown.
See where the Senate fits in the House vs. the Senate, follow the path of legislation in how a bill becomes law, or explore the larger problem in why Washington gridlocks.