The Speaker of the House of Commons votes only when necessary to break a tie.
Speaker Peter Milliken, a Liberal, did vote tonight to break a 152-152 tie on a bill adding $4.6 billion in social program spending to the federal budget, and postponing corporate tax cuts.
The Liberals survived the non-confidence motion and are now considered likely to survive until the summer recess, reducing the possibility of an immediate election call.
Constitutional experts said it was the first time in Canadian history that a House of Commons speaker was called on to break a tie on a vote to defeat a government.
But the right of the Speaker to break a tie was included in the Constitutional Act, passed in 1791.
In practise, however, the Speaker is expected under such circumstances to vote to maintain the status quo.