Canada’s Customary Obligation to Prevent Transboundary Harm and The Reduction of Emissions

Résumé

Abstract: This paper argues that the duty of prevention reaches a customary international law. Customary international law is a norm accepted broadly by states, and the parameters of this norm are explored in this paper. The central question is whether the customary duty of prevention obliges Canada to reduce greenhouse gas emissions. Under the duty, states are required to make a due diligent effort to reduce activities causing harm in other states. This effort does not necessitate an actual cessation of a particular activity. Accordingly, this paper argues that the duty of prevention can be applied in the context of reducing greenhouse gas emissions; hence, Canada is compelled to take the necessary steps to prevent the harms from such emissions, namely climate change. Carbon pricing - which Canada has adopted through the Greenhouse Gas Pollution Pricing Act - is one way to abide by the duty of prevention.