The Universal Rule of Law in the Thought of the Late Medieval Jurists of Roman and Canon Law
Late medieval Roman and canon law jurisprudence provided the origins of European notions of a universal rule of law in two senses: a legal order of universal extent and a structure of higher norms of universal application. Whereas modern international law is primarily concerned with the horizontal relationship between states, medieval jurists mainly considered the vertical relationship between universal and territorial powers. They developed de iure–de facto arguments to justify a plurality of sovereign states within an overall universal legal structure. Contributions to the elaboration of theories of just war were also made. We must be cautious about claiming that late medieval jurists contributed to the development of early international law as normally understood. Nevertheless, early-modern theorists of international law referred back to the work of their medieval juristic predecessors. A new research question is emerging about the usefulness of using the term ‘international’ in interpreting medieval jurists.