A number of other nineteenth century developments contributed to the transmutation of the law of nations into international law; that is, from aspects of a universal system of Justice into particular rules governing the relations of sovereign states. The difference is important, for although the older law of nations did cover relationships among sovereigns, this was by no means its exclusive domain. The law of nature governed sovereigns in their relationship to their own citizens, to foreigners, and to each other in a conceptually unified system. The theory of international law, which in the nineteenth century became common to virtually all writers in Europe and America, broke this unity and this universality. It lost sight of the individual almost entirely and confined itself to rules limiting the exercise of state power for reasons essentially unconnected with justice or morality save as these values might affect international relations. No longer did the sovereign look to the law of nations to determine what he ought to do; his search was merely for rules that might limit his freedom of action.

To appreciate this development, we must relate it to other aspects of nineteenth century philosophy. First, and most obvious, was the growing nationalism and the tendency to regard the state, and the individual's identification with the state, as transcending other ties of social solidarity. National identification was not new, but it was accelerating in intensity and scope throughout Europe as new unifications occurred. It reached its ultimate philosophical statement in notions of ``state will'' put forward by the Germans, especially by Hegel, although political philosophers will recognize its origins in the rejected doctrines of Hobbes. National identification was reflected jurisprudentially in law theories which incorporated this Hegelian abstraction and saw law, domestic and international, simply as its formal reflection. In the international community this reduced law to Jellinek's auto limitation. A state, the highest form of human organization in fact and theory, could be subjected to Law only by a manifestation of self-will, or consent. According to the new theories, the nineteenth century corporate sovereign was ``sovereign'' in a quite new and different sense from his historical predecessors. He no longer sought to find the law; he made it; he could be subjected to law only because he agreed to be. There was no law, domestic or international, except that willed by, acknowledged by, or consented to by states.