The course is designed to give students an introduction to the sources of international law – and the mechanisms for enforcing it. It will address the theoretical shift away from “natural-law theory” as developed in the seventeenth century to the “empirical approach” to international law - which supplanted natural-law theory in the nineteenth century and continues to provide the foundation of international law in the modern era. The readings and class-discussion will explore various contemporary theories on the process by which international custom and practice become sources of binding law – including application of the concept of “ius cogens” to human rights. The course also will examine the structure of the United Nations - with particular attention to the respective roles of the Security Council, the General Assembly, the Secretariat, and the International Court of Justice. Finally, utilizing case-studies, the course will examine how international law works in practice – focusing on jurisdiction over global commons and regulation of international commerce.