On further reflection I have come to the view that the points stated in the last paragraph are not conclusive. I am now persuaded that in the formative period of international law it is just for a representative group of power retroactively to label as criminal, conduct which, when it occurred, was universally regarded as a serious violation of generally accepted international standards and treaties. To put it in a single sentence, the reasons for my change are that the failure of the international community to attach the criminal label to such universally condemned conduct would be more likely to promote arbitrary and discriminatory action by public authorities and to undermine confidence in the proposition that international agreements are made to be kept, than the failure of the international community to abide by the maxim that no act can be punished as a crime unless there was in advance of the act a specific criminal law.
It is a choice of evil. And I do not claim that my present belief can be proved to be correct. Essentially it is what the philosophers would call a value judgment based on these considerations. If the powers had not agreed upon a rational formula for indicting those who planned World War II, it is highly probably that either some state or some unauthorized individuals would arbitrarily and perhaps even ruthlessly have undertaken the punishment of capriciously chosen Nazi chieftains. If the treaties against aggression which had been negotiated prior to World War II were treated as mere statements of intention, then post-war treaties against aggression, no matter how precisely drafted, would have been regarded as imperfect obligations.
But, regardless of its provability, the scale of values which now seems to me sound puts repugnance to retroactive legislation in a less important place than repugnance to leaving unpunished serious violations of standards universally recognized by the international community and embodied in treaties and like international obligations. To guard against misapprehension, I should reiterate that the scale applies only to grave departures from standards that have been widely and formally accepted, and only when the conduct arises in the international field where and while the organs of the international community are so undeveloped and are so intermittent in their functioning that it is impractical to expect the declaration of criminality to be made in advance of the conduct.
Thus it now seems to me to have been "just," and even probably under some civilized systems of law even "legal," to have charged the defendants with the crime of aggressive war. But, in candor, I must add that I am not satisfied that it was "legal" under American law. I can best express my reservation by example. Suppose that Hess had been brought to the United States and had been here charged with, tried on, and convicted of only the crime of aggressive war by a military tribunal created by the President with or without the cooperation of other nations; and suppose that, having been sentenced to jail in the United States, he, like Yamashita, had sought a writ of habeas corpus form a United States judge. Would he not have had a right to be released on the ground that he was held in violation of the ex post facto clause of Article I, Section 9, of the United States Constitution? That is, does not the United States Constitution put at the very front of its scale of values a ban on retroactive criminal laws?
Before turning to the next topic, I should note parenthetically that some persons who shared my original view, that before the Nuremberg trial there was no substantive "crime of aggressive war," say that even after the Nuremberg trial they do not know what the crime is, because the victorious powers and their court have not defined the crime of which the defendants were adjudged guilty. To them the verdict implies no more than the proposition that the victors are empowered to punish the vanquished. They say that there is no definition as to when a war is "aggressive" and that there is no rule laid down for distinguishing between the organizers and the participants in such an aggressive war.
To this the answers are that the definition of "aggressive," like other legal terms, will acquire content by exemplification; and the full meaning will become clear only after sufficient cases have been brought before and adjudicated by competent tribunals. It may be difficult at some future time to determine whether a particular war is an aggressive war, but there was no difficulty in deciding that the Nazi war was an aggressive war, since it would be generally conceded that the term "aggressive war" at its least includes a war like the Nazi war, which is begun by an attack by those who do not themselves believe that they are in danger of immediate attack by others. And although it may be difficult to say how far down the line of command responsibility goes, responsibility certainly extends at least to those who, knowing there is no danger, both plan and direct the unwarranted attack.
These answers would have been more evident if it had not been for the almost absurd citations of Grotius and other jurists made by some supporters of the Nuremberg proceedings. These supporters often seem to argue that Grotius said (which, of course, he did not) that those who kill in the course of a war commit a legal crime unless the war is a just war; and that where a war is unjust, those who engage in it and kill their fellow men are murderers. Grotius's definitions of just and unjust wars refer primarily not to mundane but to divine justice. And he did not describe—few sensible people would describe—as murderer the common soldier required to kill his enemy in the course of an unjust war. Neither Grotius nor the powers who drafted the Nuremberg charter nor the judges or prosecutors who participated at Nuremberg have termed criminal those men who merely fought in a war not of their making.