These volumes, arranged into five parts, bring together key writings which both illustrate and exemplify ideas that have informed the historical development of the discipline. The first part outlines three approaches, based on systems of natural laws, positivist systems and the system of 'public' international order. Parts two to four reflect aspects of the issues in the key areas of substantive law, these being sources, personality and jurisdiction and immunity. The final part takes a look into the potential futures of international law and the international legal system from a variety of perspectives.