Two-thirds vote

A supermajority, or a qualified majority, is a requirement for a proposal to gain a specified level of support which is greater than the threshold of one half used for majority.

Related concepts regarding alternatives to the majority vote requirement include a majority of the entire membership and a majority of the fixed membership.

A supermajority can also be specified based on the entire membership or fixed membership rather than on those present and voting.

Parliamentary procedure requires that any action of a deliberative assembly that may alter the rights of a minority has a supermajority requirement, such as a two-thirds vote.

Changes to constitutions, especially those with entrenched clauses, commonly require supermajority support in a legislature.

The first known use of a supermajority rule was in the 100s BCE in ancient Rome.

Pope Alexander III introduced the use of supermajority rule for papal elections at the Third Lateran Council in 1179.

In the Democratic Party of the United States, the determination of a presidential nominee once required the votes of two-thirds of delegates to the Democratic National Convention. This rule was adopted in the party's first presidential nominating convention—the 1832 Democratic National Convention. The two-thirds rule gave southern Democrats an effective veto over any presidential nominee for many years, until the rule's abolition at the 1936 Democratic National Convention.

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