It is perhaps appropriate that this symposium, in celebration of the career of Hans Baade, should conclude with some words on areas of convergence of comparative and international law-fields of the law to which Hans has devoted so much of his work over the past decades.
Of course, in a sense, the doctrines of international law have always relied to an important extent on comparative law-when that phrase is broadly understood to mean the comparison of differing doctrines, rules, and practices adopted in various legal systems. In the words of the American Restatement-echoing the well-known formulation of the Statute of the International Court of Justice-international law may result from, or be derived from, "a general and consistent practice of states followed by them from a sense of legal obligation" or "general principles common to the major legal systems."1
Certainly the determination of such "general [international] practice," or such "general principles," has always required the collection and comparison of legal and diplomatic sources from many countries of the world.2 But, in traditional views of international law, this process generally involved legal rules and diplomatic actions that were turned outward-outside the border of the country itself. Accordingly, these were doctrines and practices that were already international in nature because they concerned the treatment by one state of other states or of the citizens of other states.
For example, in the well-known American case of The Paquete Habana,3 the learned opinion of Justice Horace Gray examined numerous diplomatic acts, such as that of Louis XVI-referred to as "our ally" in the Revolutionary War-who gave "orders to the commanders of all his ships not to disturb English fishermen, nor to arrest their vessels laden with fresh fish."4 The Court also examined subsequent parallel actions of French prize tribunals, with respect to the capture by French boats of English or Portuguese vessels.5 Similarly, in the famous Lotus case, the Permanent Court of International Justice examined decisions from various countries, in order to determine whether a Turkish court could exercise criminal jurisdiction over the officer of a French ship after a collision on the high seas.6
A fundamental turning point came immediately after World War II, when, in the light of that cataclysm, international law began to shift its focus toward an area that was previously thought to lie exclusively within the realm of internal, domestic law: the treatment by one state of its own citizens-the field that we now call human rights.
Yet dramatic as this development was in 1945, its basic principles were far from new, even then. As Hersch Lauterpacht made clear in a groundbreaking book published right at the end of World War II, ideas of human rights had for centuries been bound up with many of the central ideas and concepts of natural law.7 Natural law, in turn, has long had a close, albeit somewhat uneasy, relationship with the principles of international law. Moreover, a state's treatment of the citizens of other states within its own borders-that is, a state's treatment of aliens-had been a traditional subject of international law. The same was true of a state's treatment of the citizens of other states in time of war. But the treatment by a nation of its own citizens had not emerged as a plausible subject of international law until the end of World War II.8
A rather tentative step in this direction was taken in Article 6(c) of the Nuremberg Charter, the section of the Charter that defines "crimes against humanity."9 Unlike the case of the other Nuremberg crimes-the planning and waging of aggressive war (crimes against peace) and traditional war crimes-the definition of crimes against humanity was designed to include acts by the German regime against German citizens. Yet the step was tentative because the International Criminal Tribunal at Nuremberg required that any crime against humanity-in order to be proven against the defendants-must have been committed in connection with one of the more purely international crimes set forth in the charter: that is, crimes against peace or war crimes. …