Carnation Co v Quebec (Agricultural Marketing Board) [1968] S.C.R. 238 is a leading constitutional decision of the Supreme Court of Canada on the federal authority over trade and commerce under section 91(2) of the Constitution Act, 1867. The Court held that incidental overlap of provincial laws into federal trade and commerce matters does not necessarily invalidate the law.

The issue was whether the Quebec Agricultural Marketing Board, a board created by the province, was ultra vires the authority of the province. The Court held that incidental overlap is allowed where the pith and substance of a law in intra vires the province. The Court found that the pith and substance of the Board was related to contractual rights which is valid provincial subject matter.

• Russell, P. (1989). Federalism and the Charter: Leading Constitutional Decisions. Carleton Library Series. McGill-Queen's University Press. ISBN 978-0-7735-8428-0. Retrieved 2022-07-10.