Towards a special court for the crime of aggression in Ukraine. An (im)possible path

The prosecution of crimes committed within the armed conflict in Ukraine is probably the most arduous challenge faced by the international criminal system since World War II. The involved actors have not ratified the International Criminal Court Statute, and the alleged implication of an active head of state and permanent member of the UN Security Council (Russia) with veto power, prevents the activation of mandatory jurisdiction of the Court. In this point emerges the idea of a special tribunal to judge the crime of aggression in Ukraine. Would a treaty to establish it be legitimate, considering that one stated directly incumbent would not recognise it? Would not it be a reversal of the system, since the Court was born precisely to close the ad hoc courts that proliferated in the last century?