Until about the mid-1990s, research on the Tokyo Trial centered on exploring charges pertaining to crimes against peace, or the "crime of aggression" as it is presently known in the Rome Statute of the International Criminal Court. The prosecution's case on war crimes and crimes against humanity, by contrast, came under scrutiny only in the last decade or so. This type of bias in the existing scholarship has been conditioned partly by historians' prejudgement about the nature of the trial, but more fundamentally by the inherent structural constraints of the Tokyo Trial itself.