Speaker Denison's rule is a constitutional convention established by 19th century Speaker of the British House of Commons, John Evelyn Denison, as to how the Speaker decides on his casting vote in the event of a tie.
The principle is to always vote in favour of further debate, or, where no further debate is possible, to vote in favour of the status quo.[1][2] For example, the Speaker will vote:
Speaker Denison's rule is now a guiding principle in many other bodies which have neutral chairpersons.[3]