The Constitutional Act of 1791 was a significant legislative measure taken by the British Parliament to address the governance of the Province of Quebec. Following the American Revolutionary War, many loyalists who fled to Canada settled in the western regions, leading to increasing tensions between the French-speaking population and new English-speaking settlers. To promote effective governance and alleviate conflicts, the British government decided to create two separate provinces: Upper Canada, which encompassed the western territories (mainly present-day Ontario), and Lower Canada, covering the eastern part (now Quebec). The Act outlined distinct legal and political structures for each area, establishing a legislative assembly for both provinces and allowing for greater local self-governance.

The Act's provisions included the recognition of civil law for Lower Canada, accommodating the traditions of the French-speaking populace, while Upper Canada would adopt a common law system reflective of British legal principles. The division was intended to foster loyalty to the Crown among the settlers while addressing their differing needs. This restructuring was not merely administrative; it aimed to boost economic development and stabilize a region marked by cultural diversity. The introduction of representative government and local assemblies would also lay the groundwork for future political movements in Canada.