Home Oil Distributors Ltd v. Attorney General of British Columbia [1940] S.C.R. 444 is a leading constitutional decision of the Supreme Court of Canada

Supreme Court of Canada

The Supreme Court of Canada is the highest court of Canada and is the final court of appeals in the Canadian justice system. The court grants permission to between 40 and 75 litigants each year to appeal decisions rendered by provincial, territorial and federal appellate courts, and its decisions...

 on the Trade and Commerce power under section 91(2) of the Constitution Act, 1867

Constitution Act, 1867

The Constitution Act, 1867 , is a major part of Canada's Constitution. The Act created a federal dominion and defines much of the operation of the Government of Canada, including its federal structure, the House of Commons, the Senate, the justice system, and the taxation system...

. The Court struck down the federal Coal and Petroleum Products Control Board Act, which protected the provincial market from rising gas prices, as it did not sufficiently conform to the "inter-provincial branch" of the Trade and Commerce power.
The Court found that where regulation over transactions that take place entirely within a province, even when the product has been imported, does not fall within the Trade and Commerce power and instead is a matter in the exclusive jurisdiction of the provincial government.