May I quote this well-known passage from Pascal?
“Why do you kill me? Don’t you live on the other side of the water? My friend, if you lived on this side, I would be an assassin, and it would be unjust to kill you as I am doing, but since you live on the other side, I am an honorable man, and this is just.”
Acts committed in the execution of a war are assaults on persons and goods which are themselves prohibited but are sanctioned in all legislations. The state of war could make them legitimate only if the war itself was legitimate. Inasmuch as this is no longer the case, since the Kellogg-Briand Pact, these acts become purely and simply common law crimes. As Mr. Justice Jackson has already argued before you with irrefutable logic, any recourse to war is a recourse to means which are in themselves criminal.
This is the whole spirit of the Kellogg-Briand Pact. It was intended to deprive the states which accepted it of the right of having recourse, in their national interests, to a series of acts directed against the physical persons or against the properties of nationals of a foreign power. Given this formal commitment, those who have ignored it have given the order to commit acts prohibited by the common law of civilized states, and there is here involved no special rule of international law like that which existed previously and which left the said acts of war untouched by any criminal qualifications.
A war perpetrated in violation of international law no longer really possesses the juridical character of a war. It is truly an act of gangsterism, a systematically criminal undertaking.
This war, or this would-be-war, is in itself not only a violation of international law, but indeed a crime, since it signifies the launching of this systematically criminal enterprise.
Inasmuch as they could not legally have recourse to force, those who dictated it, and who were the very organs of the state bound by treaties, must be considered as the very source of the numerous assaults upon life and property that are severely punished by all penal law.
One cannot, of course, deduce from the preceding the individual responsibility of all the perpetrators of acts of violence. It is obvious that, in an organized modern state, responsibility is limited to those who act directly for the state, they alone being in a position to estimate the lawfulness of the orders given. They alone can be prosecuted and they must be prosecuted. International law is sufficiently powerful that the prestige of the sovereignty of states cannot reduce it to impotence. It is not possible to maintain that crimes against international law must escape repressive action because, on the one hand, the state is an entity to which one cannot impute criminal intention and upon which one cannot inflict punishment and, on the other, no individual can be held responsible for the acts of the state.
On the other hand, it cannot be objected that, despite the illegality of the principle of recourse to force by Germany, other states have admitted that war existed and speak of the application of international law in time of war. It must, in fact, be noted that, even in the case of civil war, the parties have often invoked these rules which, to a certain extent, canalize the use of force. This in no wise implies acquiescence in the principle of its use. Moreover, when Great Britain and France communicated to the League of Nations the fact that a state of war existed between them and Germany as of 3 September 1939, they also declared that in committing an act of aggression against Poland, Germany had violated its obligations, assumed not only with regard to Poland but also with regard to the other signatories of the Paris Pact. From that moment on, Great Britain and France took cognizance, in some way, of the launching of an illegal war by Germany.
Recourse to war implies preparation and decision; it would be futile to prohibit it, if one intended to inflict no chastisement upon those who knowingly had recourse to it, though they had the power of choosing a different path. They must, indeed, be considered the direct instigators of the acts qualified as crimes.