Customary International Law: Research Guides & Background Information
Introduction: General Principles of Law and Other Sources
Article 38 of the International Court of Justice Statute lists customary international law and general principles of law as two of the sources of international law. These are the two most difficult sources to research because they are documented in such a wide variety of materials (e.g., state papers, diplomatic correspondence, executive decisions, judicial decisions, etc.).
Article 38 also lists judicial decisions and the teachings of international law scholars as “subsidiary means for the determination of rules of law.” These are not authorities, rather they are evidence of the sources of international law.