from the engagements of a treaty, nor modify the stipulations thereof, unless with the consent of the contracting powers by means of an amicable arrangement.” Even in 1908, when Austria-Hungary proceeded to the annexation of Bosnia-Herzegovina without obtaining the prior assent of the high contracting powers, who under the treaty of Berlin of 1878 had granted her temporary occupation of the annexed provinces, the protests of the powers concerned were answered by Austria-Hungary declaring that she had done nothing contrary to the law of nations or affecting the sanctity of treaties, because the powers had given their tacit consent to the practical transformation of her temporary into a permanent occupation.
The public opinion of the civilized world, in fact, plays in an ever-increasing degree the part of a sanctioning authority. With the growth of international intercourse and international interdependence the danger of isolation or of discredit or even of “ boycotting ” becomes a matter of increasing importance in the conduct of states. The national press and periodical literature, with exceptions no doubt, are among the chief factors in the development of this public opinion, but it is by no means dependent upon them. Personal intercourse among citizens of the same country, and between statesmen, politicians and citizens of different countries has a still greater effect in the creation of the mental attitude of nations towards each other. This exposes any departure from recognized usage or any disregard for international obligations to such re probation throughout the whole world, that, far from taking advantage of the absence of any coercive method of enforcing obedience to the principles of international law, states compete with each other in asserting their strict fidelity to such principles. And now successive diplomatic conferences have codified many of the chief branches of international usage, thus diminishing the possible cases in which states can take advantage of the uncertainty of the law and, by quibbling over its interpretation, escape from its obligations.
Sources and Foundations.-It is usual, following Wheaton's classification, ' to enumerate the sources of International Law in the following groups: text-writers of authority as witnesses of usage; treaties of peace, alliance and commerce; ordinances of particular states, prescribing rules for the conduct of their commissioned cruisers and prize tribunals; adjudications of international tribunals; written opinions of official jurists given confidentially to their own government; history of wars, negotiations, treaties and other transactions relating to the public intercourse of nations. It is in these different classes of opinions and precedents that writers have been in the habit of searching for those arguments and analogies on which have been built up the system and principles called International Law.
Wheaton, it is seen, regarded text-writers as witnesses of the usage of nations. He explains his meaning as follows: “ Without wishing to exaggerate the importance of these writers, or to substitute in any case their authority for the principles of reason, it may be affirmed that they are generally impartial in their judgment. They are witnesses of the sentiments and usages of civilized nations, and the weight of their testimony increases every time that their authority is invoked by statesmen, and every year that passes without the rules laid down in their works being impugned by the avowal of contrary principles.” This distinguished writer's quasi-explanation of the sources of International Law is extremely vague. He masses together cause and effect, private and public opinions, usage and exceptions. Professor Oppenheim has endeavoured to give a more scientific explanation of the growth and development of International Law, and objects to calling sources of International Law what are mere factors influencing its growth:-
" . . Custom and treaties, ” he observes, “are the two exclusive sources of the Law of Nations. When writers on International Law frequently enumerate other sources besides custom and treaties 1 Elements (London, 1885), pp. 22 et seq.
they confound the term ' source ' with that of ' cause ' 2 by calling sources of International Law such factors as influence the gradual growth of new rules of International Law without, however, being the historical facts out of which these rules receive their legal force. Important factors of this kind are: Opinions of famous writers on International Law, decisions of prize courts, arbitral awards, instructions issued by the different states for the guidance of their diplomatic and other organs, state papers concerning foreign politics, certain municipal laws, decisions of municipal courts. All these and other factors may influence the growth of International Law either by creating usages which gradually turn into custom, or by inducing the members of the F amilv of Nations to conclude such treaties as stipulate legal rules for future international conduct. “ A factor of the special kind which also influences the growth of International Law is the so-called comity (Comitas gentlum, Convenance et eourtoisie Internationale, Staatengunst). In their intercourse with one another states do observe not only legally binding rules and such rules as have the character of usages, but also rules of politeness, convenience and goodwill. Such rules of international conduct are no rules of law, but of cornity. The Comity of Nations is certainly not a source of International Law, as it is distinctly the contrast to the Law of Nations. But there can be no doubt that many a rule which formerly was a rule of International Comity only is nowadays a rule of International Law. And it is certainly to be expected that this development will go on in future also, and that thereby many a rule of present International Comity will in future become one of International Law." 3
We prefer to regard International Law as deriving the rules composing it from practically the same sources as domestic law, and to attribute to text-writers more or less the same value in its development as in that of the private 552 law of nations. The same primary rules of conduct are appealed to between states as between individuals, and precedents play exactly the same part wherever human actions are concerned. In both cases what has been done before commends itself when the responsibility of taking steps pledging the future is concerned. Statesmen on whom great responsibility impends, on whom the conduct of momentous negotiations has devolved, and who will have to render an account of their work to the sovereign or nation they represent, preserve an argument in their own favour in departing as little as possible from any course taken in previous similar circumstances. Precedents, moreover, are arguments for acceptance by their adversaries or counter-negotiator sf In fact, in diplomacy even more than in matters of domestic government precedents play a dominant part in the growth of usage. These precedents are often in themselves originally local usages, such as grew up in the intercourse of the Italian communities. Italy, in fact, served as a laboratory Italian
for early diplomatists and writers. It was in the m, ,, , e, ,, , e intercourse of these active and ambitious states that grew up the very notion of a foreign diplomacy and the necessity of rules of conduct in this miniature Europe, with its perpetual antagonisms and jealousies, its balance of power, its idea of a state distinct from a nation and of a community of 2 “ It seems to me, ” says Professor L. Oppenheim, “that most writers confound the conception of ' source ' with that of 'cause, and through this mistake come to a standpoint from which certain factors which influence the growth of International Law appear as sources of rules of the Law of Nations. This mistake can be avoided by going back to the meaning of the term 'source' in general. Source means a spring or well, and has to be defined as the rising from the ground of a stream of water; and, wanting to know whence it comes, we follow the stream upwards until we come to the spot where it rises naturally from the ground. On that spot, we say, is the source of the stream of water. /Ve know very well that this source is not the cause of the existence of the stream of water. Source' signifies only the natural rising of water from a certain spot of the ground, whatever natural causes there may be for that rising. If we apply the conception of source in this meaning to th-e term ' source of law ' the confusion of source with cause cannot arise. lust as we see streams of water running over the surface of the earth, so we see, as it were, streams of rules running over the area of law. And if we want to know whence these rules come, we have to follow these streams upwards until we come to their beginning. Where we find that such rules rise into existence there is the source of them. Of course, rules of law do not rise from a spot on the ground as water does; they rise from facts in the historical development of a community. Thus a. good many rules of law rise every year from the Acts of Parliament. Source of Law is therefore the name for an historical fact out of which rules of conduct rise into existence and legal force " (International Law, London, 1905, sec. 15.).
3 International Law (London, 1905) see. 19.