In the century after the fall of New France, both Indigenous peoples of Canada and French Canadians could be described as colonised peoples. Yet the treatment of each group's pre-existing laws and the ways in which each found its constitutional demands recognised (or not) varied considerably. In spite of significant rebellions in 1837-1838, French Canadians went on to achieve a high degree of autonomy within the province of Quebec in the British North America Act 1867. Meanwhile, intercultural legal arrangements with Indigenous peoples, such as the Covenant Chain, which could be termed constitutional, were gradually undermined, ignored and forgotten. This article explores the influence on these developments of changing conceptions of (English) law and of the nature of constitutions in the early to mid-nineteenth century. It argues that the decline of eighteenth-century legal pluralism and the rise of legal positivism and single-document textual constitutions played a significant role in the rise of French Canadian constitutional recognition and the corresponding decline in the perceived validity of pre-existing intercultural constitutional arrangements with Indigenous peoples.