It was introduced as a substitute for the resource allowance, which was sort of an across-the-board allowance that all resource industries got. My point of view is that there's no economic reason for there to be a deduction of royalties in the oil and gas industry against the federal income tax. Basically all it does is transfer revenues from the federal government to the province while really having no other effect.
On April 7th, 2008. See this statement in context.