What is the filibuster? How 60 votes became the rule

The filibuster is the use of the US Senate's rules on unlimited debate to delay or block a vote. Today it rarely means a senator talking for hours. A bill simply cannot move to a final vote until debate is formally closed, a step called cloture, and cloture takes 60 of the 100 senators. So in practice, most legislation needs 60 votes to pass the Senate, not a simple majority of 51.

In short

• The Senate has no general rule limiting how long its members may debate. Cloture, adopted in 1917 and set at 60 votes since 1975, is the main way to end debate.
• Most filibusters today are threats, not speeches: if 41 senators won't vote for cloture, the bill usually never comes up.
• Budget reconciliation bills and, since 2013 and 2017, all nominations can pass with a simple majority. Most other legislation still needs 60 votes.

Where did the filibuster come from?

The filibuster was an accident. The early Senate had a rule, the "previous question" motion, that a majority could use to end debate. In 1805, Vice President Aaron Burr told the Senate its rulebook was cluttered, and the motion was dropped when the rules were rewritten in 1806. No one seems to have intended it, but the Senate was left with no way to force a debate to end. Senators began to exploit that in the 1830s and 1840s.

For a century, a determined minority could talk a bill to death. In 1917, after a small group of senators blocked a bill to arm merchant ships before the United States entered the First World War, the Senate adopted Rule XXII at President Woodrow Wilson's urging. It let two-thirds of senators voting end debate. The rule was first used successfully in 1919, to close debate on the Treaty of Versailles.

The most famous filibusters came in the decades that followed, many of them against civil rights bills. Strom Thurmond of South Carolina spoke for 24 hours and 18 minutes against the Civil Rights Act of 1957, a record for an individual speech that stood until Cory Booker of New Jersey spoke for 25 hours and 5 minutes in April 2025. The Civil Rights Act of 1964 passed only after the Senate voted cloture, 71 to 29, on 10 June 1964, ending a filibuster that had run since March. It was the first time cloture had ever succeeded on a civil rights bill.

How does the filibuster work today?

In 1975 the Senate lowered the threshold for cloture to three-fifths of all senators "duly chosen and sworn", which is 60 when every seat is filled. Changing the Senate's own rules still needs two-thirds of those voting. Around the same time, leaders began running more than one bill on the floor at once, so a filibuster no longer froze all other business. That made blocking cheap. A senator no longer has to hold the floor; the minority only has to withhold its votes for cloture.

Here is what the rule asks of a bill that a minority opposes, step by step, using the timings in Rule XXII.

1. Monday. The majority leader moves to take up the bill and files a cloture petition, signed by 16 senators, to end debate on that motion.
2. Wednesday. The cloture vote takes place one hour after the Senate meets on the second day after filing. If fewer than 60 senators vote yes, the bill stalls here, and the press reports that it was filibustered.
3. Wednesday to Thursday. If cloture succeeds, the rule still allows up to 30 more hours of consideration before the Senate votes on the motion itself.
4. The next week. Debate on the bill itself is a new question, so the leader files cloture again, waits for the intervening day, wins 60 votes again, and can face 30 more hours.

Even a bill that has 60 votes can therefore take a week or more of floor time if its opponents insist on every step. That cost in time is a large part of why the majority leader chooses carefully which bills to bring up at all.

The rise in use shows in the Senate's records. Brookings treats the number of cloture motions filed as a useful proxy for filibusters, and that number has increased significantly over the 20th and 21st centuries. Because cloture is also used for routine scheduling, the count overstates filibusters somewhat, but the direction is not in doubt.

What can pass with only 51 votes?

The 60-vote rule now has large exceptions, created either by law or by the "nuclear option", in which a majority overrules the chair to set a new precedent instead of formally amending the rules.

Year	What changed	How
1974	Budget reconciliation bills, limited to taxes, spending and the debt limit, get 20 hours of debate and cannot be filibustered	Congressional Budget Act
2013	Executive-branch nominees and lower-court judges confirmed by simple majority	Nuclear option
2017	Supreme Court nominees confirmed by simple majority	Nuclear option
2019	Debate after cloture cut to 2 hours for most sub-Cabinet and district court nominees	Nuclear option
2025	Groups of executive-branch nominees below Cabinet level, not judges, may be confirmed together in one vote	Nuclear option, 11 September 2025

Dozens of narrower laws also limit debate on particular kinds of measures, such as trade agreements under fast-track rules. Reconciliation is the main route for passing major tax and spending laws without 60 votes, and both parties have used it. Its limits are policed by the Byrd rule, which strikes provisions that are mainly not about the budget.

As of mid-2026, the legislative filibuster still stood: ordinary bills still needed cloture at 60 votes. Annual spending bills are among them, which is why the filibuster figures in every fight over a government shutdown.

Should the Senate keep the filibuster?

Calls to end or change the rule come from whichever party holds the majority and finds its agenda blocked, and defenses of it from whichever party is in the minority. Both parties have switched sides on it over time.

Still argued

For keeping it, supporters argue that it forces laws to win support across parties, so they last longer and swing less when control of the Senate changes; that it protects the minority party and smaller states; and that the Senate was meant to be the slower, more deliberate chamber. For ending or limiting it, critics argue that it lets 41 senators, who can represent a small share of the population, block what most of the country wants; that it produces gridlock that pushes presidents toward acting alone; and that it was long used to stop civil rights laws. Middle positions include requiring senators to hold the floor in a "talking filibuster", carving out particular kinds of bills, and procedural changes, such as dropping the intervening day or shortening debate, that would keep the 60-vote threshold but let the majority get past delays faster. Which outcome is better depends on how much weight one gives to majority rule against stability and minority protection, and that is a judgment, not a fact.

The filibuster is one reason the Senate is so different from the House, where a simple majority controls the floor. How a bill becomes a law follows a bill through both chambers, and what Congress does sets out the Senate's other powers. The underlying tension between majority rule and protecting minorities runs through democracy itself.

Check yourself

• Without looking back: why does a bill need 60 votes in the Senate when the Constitution only asks for a majority?
• What changed in the 1970s that made filibustering cheap?
• Name two things the Senate can now pass or confirm with 51 votes, and how each exception came about.

Sources

• Filibuster and cloture — United States Senate
• Longest filibusters — United States Senate
• Rules of the Senate, Rule XXII — Senate Committee on Rules and Administration
• What is the Senate filibuster, and what would it take to eliminate it? — Molly E. Reynolds, Brookings, 2021
• The Filibuster, Explained — Brennan Center for Justice, updated 2025
• Senate Republicans invoke 'nuclear option' to change rules for nominees — The Washington Post, via The Spokesman-Review, 2025