The precautionary principle has emerged as one of the most contentious international norms within international environmental law. Yet, despite the vexing conceptual uncertainties confronting the precautionary principle, it is repeatedly invoked by policy makers and incorporated within international and domestic environmental law and agreements. This thesis explores how the international norm of precaution comes to be translated from the international sphere to domestic public policy. The research utilizes the pathways framework, which suggests that there are three additional pathways in additional to the direct implementation of international rules in national law and policy - international norms and discourse, markets and direct access - through which actors, institutions and interests can influence domestic and firm-level policy change. The findings propose an explanation of why Canada came to adopt a particular version of the precautionary principle, also revealing the complex nature of norm transfer, the significance of multiple causal pathways of influence and the interactions arising along these pathways.