The procedure for "invoking cloture," or ending a filibuster, is as follows:
- A minimum of sixteen Senators must sign a petition for cloture.
- The petition may be presented by interrupting another Senator's speech.
- The clerk reads the petition.
- The cloture petition is ignored for one full day during which the Senate is sitting (If the petition is filed on a Friday, it is ignored until Tuesday, assuming that the Senate did not sit on Saturday or Sunday.)
- On the second calendar day during which the Senate sits after the presentation of the petition, after the Senate has been sitting for one hour, a "quorum call" is undertaken to ensure that a majority of the Senators are present.
- The President or President pro tempore presents the petition.
- The Senate votes on the petition; three-fifths of the whole number of Senators (sixty with no vacancies) is the required majority; however, when cloture is invoked on a question of changing the rules of the Senate, two-thirds of the Senators voting (not necessarily two-thirds of all Senators) is the requisite majority.
- No more than thirty hours of debate may occur.
- No Senator may speak for more than one hour.
- No amendments may be moved unless they were filed on the day in between the presentation of the petition and the actual cloture vote.
- All amendments must be relevant to the debate.
- Certain debates on procedure are not permissible.
- The presiding officer gains additional power in controlling debate.
- No other matters may be considered until the question upon which cloture was invoked is disposed of.
In current practice, Senate rules permit procedural filibusters, in which actual continuous floor speeches are not required, although the Senate majority leader may require an actual traditional filibuster if he so chooses.
Another meaning of filibuster, and perhaps the original one, is where a private individual with a mercenary force attempts or accomplishes an invasion or a revolution in a foreign state, with an aim towards establishing himself as its ruler. A good example of this type of filibuster was William Walker's campaign in Nicaragua.External link