An introduction to public international law that both governs the global commons—atmosphere, climate, oceans, and stratospheric ozone layer—and guides the national obligations for ensuring transnational public health, advancing sustainable development, and managing the Earth’s shared resources: sources of energy and renewable stocks of plants and animals, biodiversity, and ecosystems services. The course explores how environmental law builds upon general principles of international law; the evolving norms of humanitarian law, human rights, environmental rights, and the rights of nature; and the substantive and procedural treaty obligations of nations. The principal multilateral environmental agreements (MEAs) are studied, with attention to how states enact environmental law regimes to implement the MEAs. Decision-making procedures of United Nations agencies and other international and regional bodies are critically examined. The main texts are a law school casebook, D. Hunter, D. Zaelke, and J. Salzman, International Environmental Law and Policy(Foundation Press, 2002), and the UN Environment Programme’s commissioned restatement of this body of law, N.A. Robinson and L. Kurukulasuriya, Manual on International Environmental Law(UNEP, 2006). The course concludes with a written final examination.