Canada's Constitution is the supreme law of the country, establishing the fundamental framework for how government operates and defining the relationship between citizens and the state. Key elements include the Constitution Act, 1867 (originally the British North America Act) which established Confederation and divided powers between federal and provincial governments, and the Constitution Act, 1982 which patriated the Constitution from Britain and added the Charter of Rights and Freedoms. The Constitution can only be changed through difficult amendment processes requiring substantial federal and provincial agreement. All other laws must comply with the Constitution—courts can strike down laws that violate constitutional provisions.