INTERNATIONAL LAW, that code of rules by which nations have agreed to be governed in their relations with each other. It differs from the codes of law governing the internal affairs of individ ual states in the fact that its rules are less definitely fixed and that there is no authority behind and above it, with power to interpret or enforce its provi sions and to punish those guilty of vio lating them. In the absence of such judicial and administrative authority, it depends for its vitality upon the good faith and mutual understanding of those by whom and for whom it has been cre ated, quickened by a wholesome respect for the opinion of the world and an equally wholesome realization of the consequences which may follow upon its violation. The world has re cently had a striking demonstration of what these consequences may be in an ex treme case, and as a result of this demon stration it is safe to say that Interna tional Law which in 1914 seemed to be dead, is in 1921 more vigorously alive than it has ever been at any previous period in its history.
The fundamental principles of Inter national Law are fairly well established. In theory they coincide with the prin ciples of justice, humanity, courtesy and reasonableness which are supposed to regulate the relations of individuals in their intercourse with each other in any civilized and especially in any Christian community. The rules governing the ap plication of the principles to specific questions arising between nations are iess clear, and it is in this field chiefly that differences arise between nations, passing frequently into disputes and not infrequently into wars. It is in this field, also, that progress is being con stantly made through international con ferences and arbitral decisions. If the progress thus far made does not give promise of immediate universal peace, it gives promise at least of a general understanding such as will make it con stantly more difficult to justify war by manufactured grievances.
The beginnings of International Law coincide with the beginnings of interna tional relations. No sort of peaceful in tercourse between nations or cities or even tribes can be conceived without as suming some rules governing such in tercourse. A well developed, though
limited, code existed between the city states of Greece of which Athens and Sparta were the leaders, and between the Latin city-states of early Roman history. With the extension of the Roman power until it covered the civil ized world, the necessity for " inter national " rules ceased to exist. The law of Rome was the law of the world.
In the first few centuries following the fall of Rome, Roman civilization and culture, including Roman Law, were as similated by the new nations of NVestern Europe. With the conquests of Charle magne and his assumption of the im perial title in 800, the Roman tradition took on a new lease of life; and for many centuries thereafter the fiction per sisted of a " Holy Roman Empire " with a dual government of Church and State, claiming universal sovereignty and so keeping alive the conception of a super state and a super-law. Thus it came about that when the modern world, in the middle of the seventeenth century emerged from the desolation of the Thirty-Years War, and thoughtful men began to seek for something in the way of an agreement that should make for a better understanding between nations, they found a code existing whose under lying principles could be adapted to in ternationalization, and a world to which the conception of such internationaliza tion was not entirely strange. They found existing also a treatise on " The Law of Peace and War" in which the transition from national to international law was indicated with remarkable pre cision and a new and broader code de veloped in which full weight was given to international customs already existing and to the principles of humanity and morality which are the basis of Christian civilization and ethics. This treatise, published at Paris in 1625 by a Dutch jurist, Hugo Grotius, the " Father of In ternational Law," marks the beginning of a new era in international relations and in the development of International Law as a science.