<P> The concept of a casting vote is not used in Robert's Rules of Order . </P> <P> Under some rules of parliamentary procedure, notably Robert's Rules of Order, the presiding officer does not have a casting vote in the way it is normally understood as a means to break ties . Instead, he or she has a normal vote, but exercises it only after other members have voted, and only if it would make a difference . This allows the presiding officer to vote against a motion to bring it to a tie and defeat it (for instance, if the vote is 50 - 49, the presiding officer could defeat the vote by voting against) in addition to breaking a tie by voting in favour . The intent behind this rule is to give the presiding officer the same voting rights as other members while preserving their impartiality whenever possible, by not having them vote unless it would change the outcome . </P> <P> Some legislatures 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 . </P> <P> 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 usually votes in general debates, commonly based on party lines . The President does not have a casting vote, and a tied vote in the Senate is resolved in the negative . The same arrangements exist with respect to the Speakers of the Canadian House and Senate . </P>

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