This dissertation analyzes some of the ways in which ?constitutional architecture? shapes jurisprudence in Canada and the United States, with a particular focus on appellate court decisions related to aboriginal and environmental law. The purpose of the comparison is to consider how the differences between parliamentary government and American-style ?separation of powers? affect the nature of judicial power, as well as how differences in the language of the Canadian and American constitutionalism shape the direction of law in the two countries. In contrast to those political scientists who interpret law as being driven by political factors, this dissertation emphasizes the ways in which institutional structures place limits on the scope of judicial ideology and judicial activism. In other words, political jurisprudence takes place within the limits established by constitutional architecture. The project is based on an analysis of environmental and aboriginal law decisions decided by the Supreme Courts of Canada and the United States between 1985 and 2007, as well as an analysis of environmental policy cases decided by American and Canadian federal courts of appeal. The key conclusion is that constitutional differences, not ideology, explain the differing opportunities for the ?judicialization? of environmental and aboriginal policy in Canada and the United States. In the USA, the separation of powers is the principal source of judicialization of environmental policy; in Canada, the Parliamentary system restrains the ability of an otherwise activist judiciary to shape the implementation of environmental law. In regards to aboriginal policy, in contrast, the Canadian constitution has provided a basis for judicial activism. The cases of environmental and aboriginal law illustrate that, in Canada and the United States, institutional constraints continue to determine the limits of political jurisprudence.