Customary International Law and Public Goods

The paper examines the potential of customary international law to protect global public goods. In particular, it focuses on the question whether customary law can contribute to the mitigation of climate change. The analysis proceeds in the three steps. First, it will have a closer look at the concept of public goods and common pool resources in economic theory and experimental economics. On this basis, the second section examines the formation of customary international law. The analysis shows that sustaining cooperation in multilateral settings through customary law is difficult. With regard to the mitigation of climate change, it is unlikely that states will coordinate on an equilibrium that will lead to a reduction of greenhouse gas emissions. The section then examines two further ways of identifying customary international law through moral interpretation and judicial lawmaking. However, the potential of these two avenues to protect global public goods effectively is rather limited. The final section analyzes the protection of global public goods through the initially unilateral extension of authority. One problem of global public goods is that states have shared authority over them. A solution might be to divide authority by extending the jurisdiction of the nation states. I will draw from an example concerning the protection of common pool resources, the protection of fish stocks, and analyze whether this example contains any lessons for the mitigation of climate change.