Supreme Court: Interjurisdictional Immunity Remains Essential Constitutional Doctrine

Although federal and provincial governments have exclusive heads of power under Canada's Constitution Act, 1867, in practice, there can be overlap in the types of activities that both governments can regulate. But not all overlap is permitted. A key constitutional doctrine—interjurisdictional immunity—prevents the laws of one government from impairing the core of the other's legislative powers. In 2007, the Supreme Court of Canada signaled that this doctrine should be applied with restraint. But more recent cases have confirmed that it remains an important and robust tool. In Opsis Airport Services Inc. v. Québec (Attorney General)¹, the Supreme Court affirmed this trend, stressing the continued importance of interjurisdictional immunity. The Court also indicated it may be applied more flexibly in the future.