veto

Exercise by a sovereign, branch of legislature, or other political power, of the right to prevent the enactment or operation of a law, or the taking of some course of action.

Under the US Constitution, the president may veto legislation, although that veto may, in turn, be overruled by a two-thirds majority in Congress. Bills also become law if the president does not sign them within ten days of their passing through Congress, but this applies only when Congress is in session, so that bills which are presented for approval less than ten days before the end of the session may be subject to what is known as the president's pocket veto. This can assume considerable significance since there is a tendency for legislation to bank towards the end of a congressional session. A 1996 act gave future presidents a ‘line-item’ veto over specific items in spending bills, significantly increasing presidential authority. The act met with legal challenge, however, because it was seen as upsetting the balance of power between the executive and legislative branches of the government. A definitive ruling was mid-1998 awaited from the Supreme Court.

The term originates in the power of the tribunes of the plebs of ancient Rome to declare their protest against any unlawful measure.

The exercise of the veto has been of great importance in the operations of the Security Council of the United Nations. Each of the five permanent members of the Council, the USA, Russia, the UK, France, and China has the right to veto any resolution. Russia originally proposed that unanimity among the five was necessary, but eventually agreed to the veto. Apart from China each of the powers has made use of the veto from time to time, but none more than the former USSR.