The Supreme Court has the ultimate power of judicial review over Canadian federal and provincial laws' constitutional validity. If a federal or provincial law has been held contrary to the division of power provisions of one of the various Constitution Acts, the legislature or Parliament must either live with the result, amend the law so that it complies, or obtain an amendment to the constitution. If a law is declared contrary to certain sections of the Charter of Rights and Freedoms, Parliament or the provincial legislatures may make that particular law temporarily valid again against by using the ''override power'' of the notwithstanding clause. In one case, the Quebec National Assembly invoked this power to override a Supreme Court decision (Ford v. Quebec (A.G.)) that held that one of Quebec's language laws banning the display of English commercial signs was inconsistent with the charter. Saskatchewan used it to uphold labour laws. This override power can be exercised for five years, after which time the override must be renewed, or the decision comes into force.