What is a filibuster?

The filibuster is most famously associated with the US Senate, where rules allow senators to keep debating unless a supermajority votes to end discussion. Since 1975, ending debate on most legislation, a process called cloture, requires 60 of the 100 senators. The longest individual speech was by Senator Strom Thurmond, who spoke for 24 hours and 18 minutes in 1957 against a civil rights bill. In 2025 Senator Cory Booker broke that record with a speech of just over 25 hours. The word comes from a Dutch term for freebooter, or pirate, via Spanish 'filibustero'.