What is the constitutional amending formula?

The constitutional amending formula is the procedure for amending the Canadian Constitution, set out in Part V (sections 38 to 49) of the Constitution Act, 1982. The amending formula has five different procedures depending on the type of amendment. The formula gives the federal Parliament and the provincial Legislatures (and in some cases the Senate) different roles in different types of amendments.

The general procedure (section 38) requires consent of the federal Parliament and the Legislative Assemblies of at least seven provinces representing at least 50 per cent of the population (the '7-and-50' rule). This is the default procedure for most amendments. Section 38 includes a provincial opt-out provision: any province whose legislature passes a resolution dissenting can be exempted from an amendment that derogates from provincial powers.

The unanimity procedure (section 41) requires consent of Parliament and all 10 provincial Legislative Assemblies. Section 41 covers five specific matters: (a) the office of the King, the Governor General, or the Lieutenant Governor of a province; (b) the right of a province to a number of MPs not less than the number of senators representing the province; (c) the use of English or French as official languages; (d) the composition of the Supreme Court of Canada; and (e) any amendment to Part V itself (the amending formula).

Three other procedures cover specific matters. Section 43 covers amendments affecting only one or more (but not all) provinces, requiring consent of Parliament and the legislatures of the affected provinces. Section 44 allows the federal Parliament to amend matters within exclusive federal jurisdiction (such as the federal executive or the House of Commons) by federal statute alone. Section 45 allows provincial Legislatures to amend their provincial constitutions by provincial statute alone, subject to certain limits. Major amendments since 1982 have been comparatively few because of the difficulty of meeting the formula. Successful amendments have included the 1983 Constitution Amendment Proclamation (improving Indigenous rights protection), the 1993 New Brunswick amendment (entrenching official bilingualism), the 1997 Newfoundland amendment (replacing denominational schools), and the 2001 Newfoundland Act amendment (renaming the province Newfoundland and Labrador). The failed Meech Lake (1987) and Charlottetown (1992) accords both attempted comprehensive constitutional reform.