A casting vote is a vote given to the presiding officer of a council or legislative body to resolve a deadlock and which can be exercised only when such a deadlock exists. Examples of officers who hold casting votes are the Speaker of the British House of Commons and the Vice President of the United States (in his constitutional capacity as President of the United States Senate).
In some legislatures, a casting vote may be exercised however the presiding officer wishes. An example is the Vice President of the United States, who may exercise his casting vote in the Senate according to his party affiliation or according to his own personal beliefs. By virtue of the Vice President's casting vote, when the Senate as elected is equally divided between two parties, the Vice President's party automatically becomes the official majority party in the Senate. The exercise of the Vice President's casting vote has become increasingly rare throughout American history as the size of the Senate has grown from 26 to 100 and ties have become less probable.
In some other legislatures, by contrast, a casting vote can only be exercised according to strict rules or conventions. For example, the Speaker of the British House of Commons is expected by constitutional convention to follow Speaker Denison's rule, i.e. to vote to allow further discussion, if this is possible, and otherwise to vote against the proposal concerned.
Some countries have abandoned the concept of a casting vote. For example, the Speaker of the New Zealand House of Representatives formerly held a casting vote similar to that of the Speaker of the British House of Commons. Today, however, the Speaker simply votes as an ordinary member, and since an outright majority is necessary for a bill to pass, a tie is considered to be a defeat.
Some legislatures have a dual approach. In the Australian Parliament, the Speaker of the House of Representatives may not vote in general debates but has a casting vote to decide a tie. The President of the Senate may vote in general debates but, to preserve the appearance of impartiality, rarely if ever does so. The President does not have a casting vote, and a tied vote in the Senate is resolved in the negative.
While having the same right to vote as any member of the House, the Speaker of the United States House of Representatives, in order to maintain the appearance of impartiality, typically does not vote unless his or her vote will make the difference. As there are 435 Congressmen, an odd number, this is in effect a casting vote.
Casting vote at elections
At one time, in United Kingdom parliamentary elections, the Returning officer (if an elector in the constituency) was allowed to give an additional casting vote to decide the election if there was a tie between two or more candidates. An example of this power being used was in the Bandon by-election of 22 July 1831. This type of casting vote does not now exist, as modern electoral ties in the United Kingdom are broken by drawing lots using a method decided upon by the returning officer.
- "General Election 5th May 2005 Briefing Information (application/pdf Object)". UK Department of Constitutional Affairs. pp. p33. Retrieved 2009-02-20.