The nuclear, or constitutional, option is a parliamentary procedure that allows the United States Senate to override its own rules by majority vote. Senate rules require a three fifths, or 60 vote, "supermajority" to reach a decision in many situations. If the presiding officer rules that a motion raises a constitutional issue, the matter goes immediately to the full senate. Since the Senate decides a constitutional issue by majority vote and without debate, this procedure bypasses the supermajority requirement. The procedure has been used only a few times in Senate history. Constitutionally, the presiding officer of the Senate has the same discretionary power as the Speaker of the House. But in most situations, he simply follows precedent as interpreted by the parliamentarian.
In 1892, the U.S. Supreme Court ruled in United States v. Ballin that the House of Representatives is a parliamentary body and as such may establish rules by majority vote. The rules may not violate fundamental rights or constitutional restraints, according to this opinion. Mason's Manual, followed by U.S state legislatures, applies the principle to legislative bodies generally: "A deliberative body cannot by its own act or rule require a two-thirds vote to take any action where the constitution or controlling authority requires only a majority vote. To require a two-thirds vote, for example, to take any action would be to give to any number more than one-third of the members the power to defeat the action and amount to a delegation of the powers of the body to a minority."
It has been argued that Ballin does not apply to the Senate because the Senate is in continuous session. As president of the Senate, Vice President Richard Nixon responded to a parliamentary inquiry on this matter in 1957. Nixon's opinion states that the constitution grants the presiding officer the authority to disregard Senate rules, provided that his ruling is later upheld by majority vote. The procedure Nixon outlined was used for the first time by Vice President Hubert Humphrey in 1967. On this occasion, the Senate upheld precedent and did not support the presiding officer. In 1975, the procedure was used three times. The Senate initially voted to support the presiding officer each time, overturning precedent. These votes were later reversed as part of a compromise that featured a dramatic reform of the filibuster. Senator Trent Lott applied the name "nuclear option" to the procedure in 2003. It was used again in November 2013 to revise rules concerning judicial and administrative nominations. Except for supreme court justice, these may now be confirmed by majority vote.
- Mason's Manual of Legislative Procedure, p, 353, 2000.
- Martin Gold, Dimple Gupta, "The constitutional option to change Senate rules and procedures: A majoritarian means to overcome the filibuster", Harvard Journal of Law and Public Policy, 2004.