The Oxford ILDC online database, an online collection of domestic court decisions which apply international law, has been providing scholars with insights for many years. This casebook introduces key court decisions with brief introductory and connecting texts. An ideal text for practitioners, judges, and government officials, as well as for students of international law courses, the casebook explains the theories and doctrines underlying the use by domestic courts of international law and illustrates the key importance of domestic courts in the development of international law. It consists of five parts. Part I discusses the vertical relationship between international law and domestic law, looking at validity and supremacy, the standing of private parties to invoke it, direct effect, as well as avoidance and contestation. Part II focuses on the structural and procedural areas of international law, specifically statehood, jurisdiction, immunities, and international organizations. In Part III, sources of international law are detailed, looking at the law of treaties, customary international law, jus cogens, soft law, and international court decisions. Part IV addresses responsibility and redress, covering international responsibility and private remedies. Finally, Part V reviews substantive and functional areas of international law, including: terrorism, use of force, international humanitarian law, international criminal law, amnesties, economic and social rights.