(Violation of the laws and customs of war Carnegie Endowment for International Peace ; DIVISION OF INTERNATIONAL LAW, Pamphlet No. 82 Reports of Majority and Dissenting Reports of American and Japanese members of the Commission of Responsibilities. conference of Paris May 18, 1919)
p.151: Reservations by the Japanese delegation:
A question may be raised whether it can be admitted as a principle of the law of nations that a high tribunal constituted by belligerents can, after a war is over, try an individual belonging to the opposite side, who may be presumed to be guilty of a crime against the laws and customs of war, It may further be asked whether international law recognizes a penal law as applicable to those who are guilty.
p.152: Our scruples become still greater when it is a question of indicting before a tribunal thus constituted highly placed enemies on the sole ground that they abstained from preventing, putting an end to or repressing acts in violation of the laws and customs of war, as is provided in clause c of section b of article IV.