Manitoba (AG) v Manitoba Egg and Poultry Association (the Manitoba Egg Reference) [1971] S.C.R. 689 is a leading Supreme Court of Canada decision on the Trade and Commerce power under section 91(2) of the Constitution Act, 1867. The decision was the result of a growing political debate known as the "chicken and egg war" where Quebec and Ontario enacted protectionist legislation for the egg and poultry industry preventing Manitoba from selling their eggs and poultry products in those provinces. To much of the public's surprise the Court struck down a provincial statute regulating the marketing of eggs. The case somewhat contradicted the precedent case of Carnation Co. v. Quebec Agricultural Marketing Board, [1968] S.C.R. 238 which held that provincial law that has an incidental effect on other provinces is still valid.
