The plaintiff First Nation brought an action against Canada and Ontario for failing to set aside a reserve for them under Treaty No. 9 in 1906.
The parties agreed that a reserve should have been set aside.
The threshold issue at trial was determining the 'crystallization date'—the point in time at which the band's population should be assessed to calculate the size of the reserve.
The plaintiffs argued the population should be determined as of the date the reserve is actually set aside or the date of the court's declaration.
The Crown argued the population should be determined as of the date the treaty was made.
The court held that the common intention of the parties, based on the text of the treaty and its historical context, was that reserves were to be set aside and sized according to the population at the time the treaty was made.
