Quebec (AG) v Blaikie (No 1)
Quebec (AG) v Blaikie (No 1), [1979] 2 S.C.R. 1016 is a leading decision of the Supreme Court of Canada on language rights in the Constitution Act, 1867. The Court held that the sections of Quebec's Charter of the French Language (better-known at the time as "Bill 101"), which required that provincial laws be enacted in French only, violated section 133 of the Constitution Act, 1867.
Source: Wikipedia — Quebec (AG) v Blaikie (No 1) (CC BY-SA 4.0)