Writing in 1964, Pieter Kooijmans challenged the principle of legal equality of states: it would have to prove its value or be discarded. He also predicted the relevance of the principle for a new subject of international law: the individual. Almost fifty years later, this article reviews how the principle has fared in international criminal law, a field of international law relevant both to states and to the individual. The review shows how the emergence of a more vertical international legal order has weakened the position of the principle of equality between states. The weakening of the principle in the relation between states has in turn affected the equality between individuals, which has contributed to further actual inequality between states. Contrary to one of Kooijmans's scenarios, the emerging international legal order has not diminished the role of the ‘factual conditions of power politics’. Legal questions on permitted differentiations always involve inherently political assessments. For instance, Kooijmans's concept of ‘juridically relevant’ differences requires a determination of which differences are ‘of intrinsic value for the existence of legal order’, and thus a decision on what that order should look like and how it is to be pursued. Moreover, factual conditions of power politics continue to encroach upon the principle of legal equality. Perhaps the principle of legal equality, like the fight against impunity, is more of an ideal than a reality. But the pursuit of the fight against impunity has thus far undermined the fight for more equality.