This paper addresses the tension between the traditionally dualist or ‘territorial’ take on division of powers, on the one hand, and a more functional conception of federalism, on the other hand, and the place of cooperative federalism within that structure. Part 1 will briefly address these two contrasted visions of Canadian federalism, by focusing on the writings of two former Supreme Court Justices, Jean Beetz and Bora Laskin. In particular, this Part will highlight how each author considered the potential, and limitations, of cooperative federalism. Part 2 will draw a portrait of cooperative federalism in Canada, by looking at both judicial cooperative federalism, at play when courts tone down the effect of rigid constitutional law doctrines, and executive cooperative federalism, which inspires Courts’ deference when integrated or interlocked cooperative regimes are challenged. Finally, the last part of this paper will take the securities regulation debate as a focal point for considering the past, and potential, role of cooperative federalism in the second round of litigation which is just starting.