The first article of the draft Treaty for Mutual Assistance of 1923 read in these terms:
“The High Contracting Parties, affirming that aggressive war is an international crime, undertake the solemn engagement not to make themselves guilty of this crime against any other nation.”
In the Preamble to the Geneva Protocol of 1924, it was stated that “offensive warfare constitutes an infraction of solidarity and an international crime.” These instruments that I have just last mentioned remained, it is true, unratified for various reasons, but they are not without significance or value.
These repeated declarations, these repeated condemnations of wars of aggression testified to the fact that with the establishment of the League of Nations, with the legal developments which followed it, the place of war in international law had undergone a profound change. War was ceasing to be the unrestricted prerogative of sovereign states. The Covenant of the League of Nations did not totally abolish the right of war. It left, perhaps, certain gaps which were possibly larger in theory than in practice. But in effect it surrounded the right of war by procedural and substantive checks and delays, which, if the Covenant had been faithfully observed, would have amounted to an elimination of war, not only between members of the League, but also, by reason of certain provisions of the Covenant, in the relations of non-members as well. And thus the Covenant of the League restored the position as it existed at the dawn of international law, at the time when Grotius was laying down the foundations of the modern law of nations and established the distinction, a distinction accompanied by profound legal consequences in the sphere, for instance, of neutrality, between a just war and an unjust war.
Nor was that development arrested with the adoption of the Covenant of the League. The right of war was further circumscribed by a series of treaties, numbering—it is an astonishing figure but it is right—nearly a thousand, of arbitration and conciliation embracing practically all the nations of the world. The so-called Optional Clause of Article 36 of the Statute of the Permanent Court of International Justice, the clause which conferred upon the Court compulsory jurisdiction in regard to the most comprehensive categories of disputes, and which constituted in effect by far the most important compulsory treaty of arbitration in the postwar period, was widely signed and ratified. Germany herself signed it in 1927 and her signature was renewed, and renewed for a period of 5 years by the Nazi government in July of 1933. (Significantly, that ratification was not again renewed on the expiration of its 5 years’ validity in March of 1938 by Germany). Since 1928 a considerable number of states signed and ratified the General Act for the Pacific Settlement of International Disputes which was designed to fill the gaps left by the Optional Clause and by the existing treaties of arbitration and conciliation.
And all this vast network of instruments of pacific settlement testified to the growing conviction throughout the civilized world that war was ceasing to be the normal or the legitimate means of settling international disputes. The express condemnation of wars of aggression, which I have already mentioned, supplies the same testimony. But there was, of course, more direct evidence pointing in the same direction. The Treaty of Locarno of the 16th October 1925, to which I shall have occasion to refer presently, and to which Germany was a party, was more than a treaty of arbitration and conciliation in which the parties undertook definite obligations with regard to the pacific settlement of disputes which might arise between them. It was, subject to clearly specified exceptions of self-defense in certain contingencies, a more general undertaking in which the parties to it agreed that “they would in no case attack or invade each other or resort to war against each other.” And that constituted a general renunciation of war, and it was so considered to be in the eyes of international jurists and in the public opinion of the world. The Locarno Treaty was not just another of the great number of arbitration treaties which were being concluded at this time. It was regarded as a kind of cornerstone in the European settlement and in the new legal order in Europe in partial, just, and indeed, generous substitution for the rigors of the Treaty of Versailles. And with that treaty, the term “outlawry of war” left the province of mere pacifist propaganda. It became current in the writings on international law and in the official pronouncements of governments. No one could any longer say, after the Locarno Treaty—no one could any longer associate himself with the plausible assertion that at all events, as between the parties to that treaty, war remained an unrestricted right of sovereign states.
But, although the effect of the Locarno Treaty was limited to the parties to it, it had wider influence in paving the way towards that most fundamental, that truly revolutionary enactment in modern international law, namely, the General Treaty for the Renunciation of War of 27 August 1928, the Pact of Paris, the Kellogg-Briand Pact. That treaty, a most deliberate and carefully prepared piece of international legislation, was binding in 1939 on more than 60 nations, including Germany. It was, and it has remained, the most widely signed and ratified international instrument. It contained no provision for its termination, and it was conceived, as I said, as the cornerstone of any future international order worthy of the name. It is fully part of international law as it stands today, and it has in no way been modified or replaced by the Charter of the United Nations. It is right, in this solemn hour in the history of the world, when the responsible leaders of a state stand accused of a premeditated breach of this great treaty which was, which remains, a source of hope and of faith for mankind, to set out in detail its two operative articles and its Preamble. Let me read them to the Tribunal—first the Preamble, and it starts like this:
“The President of the German Reich”—and the other states associated . . .
THE PRESIDENT: Shall we find it among the documents?
SIR HARTLEY SHAWCROSS: It will be put in. I don’t think you have it at the moment.
“The President of the German Reich . . . deeply sensitive of their solemn duty to promote the welfare of mankind; persuaded that the time has come when a frank renunciation of war as an instrument of international policy should be made to the end that the peaceful and friendly relations now existing between their peoples may be perpetuated; convinced that all changes in their relations with one another should be sought only by pacific means and be the result of a peaceful and orderly progress, and that any signatory power which shall hereafter seek to promote its national interests by resort to war, should be denied the benefits furnished by this Treaty; hopeful that, encouraged by their example, all the other nations of the world will join in this humane endeavor and by adhering to the present treaty as soon as it comes into force bring their peoples within the scope of its beneficent provisions, thus uniting civilized nations of the world in a common renunciation of war as an instrument of their national policy . . . .”
Then, Article I:
“The High Contracting Parties solemnly declare in the names of their respective peoples that they condemn recourse to war for the solution of international controversies and renounce it as an instrument of national policy in their relations with one another.”
And Article II:
“The High Contracting Parties agree that the settlement or solution of all disputes or conflicts of whatever nature or of whatever origin they may be, which may arise among them, shall never be sought except by pacific means.”
In that treaty, that General Treaty for the Renunciation of War, practically the whole civilized world abolished war