Article 38 of the Statute of the International Court of Justice (ICJ) defines “international law” to include not only “custom” and “convention” between States but also “the general principles of law recognized by civilized nations” within their municipal legal systems. In 1953, Bin Cheng wrote his seminal book on the general principles, identifying core legal principles common to various domestic legal systems across the globe. With the growth of inter-state intercourse, the use of general principles has dramatically increased over the past 60 years. In addition to the ICJ, international law is now regularly applied by domestic courts and international arbitral tribunals in myriad settings. General principles of international law can serve as rules of decision, whether interpreting investment defined in treaties or contracts, determining causation, or ascertaining unjust enrichment. They also include a core set of procedural requirements that should be followed in any adjudicative system, such as the right to impartiality and the prohibition on fraud. Although the general principles are, by definition, basic and even rudimentary, they hold vital importance for the rule of law in international relations. They are meant not to define a rule of law, but rather the rule of law. This monograph summarizes and analyzes the general principles of law and norms of international due process, with a particular focus on developments since Cheng’s writing. In one volume, it collects and distills these principles and norms as a practical resource for international law jurists, advocates, and scholars.