In the chapter on “Law and Legal Process in International Affairs,” in my book The United States and the Rule of Law in International Affairs, I begin with the lead-in to each program in the Monty Python BBC television series: “And now for something completely different.” Law and legal process in international affairs are indeed vastly if not completely different from their counterparts in national legal systems. Moreover, it is this vast difference from national law and practice that has given rise to much skepticism about international law and practice and to challenges to claims of its “legal” nature and of its relevance to the conduct of international affairs.

Interestingly, in the early history of international law, there was much less skepticism about international law as “law” and its relevance to international affairs. The end of the Thirty Years War in 1648 and the resultant Peace Treaties of Westphalia are regarded by most historians and international lawyers as the beginning of modern international relations and therefore of modern international law. But prior to the Peace of Westphalia, “an intensification of international trade, improvements in navigation and military techniques, and the discovery of many distant lands … stimulated the further development of international practices and the emergence of modern conceptions of a law of nations.” In particular, the Hanseatic League, created in the thirteenth century by certain German city-states and by the early fifteenth century comprising more than 150 trading cities and centers, contributed substantially to the growth of international usages and customs.