The Constitution Act, 1867, originally enacted as the British North America Act, 1867, is a major part of the Constitution of Canada. 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. In 1982, with the patriation of the Constitution, the British North America Acts which were originally enacted by the British Parliament, including this Act, were renamed. However, the acts are still known by their original names in records of the United Kingdom. Amendments were also made at this time: section 92A was added, giving provinces greater control over non-renewable natural resources.

The Constitution of Canada is the supreme law in Canada. It outlines Canada's system of government and the civil and human rights of those who are citizens of Canada and non-citizens in Canada. Its contents are an amalgamation of various codified acts, treaties between the Crown and Indigenous Peoples, uncodified traditions and conventions. Canada is one of the oldest constitutional monarchies in the world.