In the mid-1940s following the Allied victory in World War II, a Nuremberg court held historic trials against Nazi officials, with a second trial in Tokyo aimed at into Japanese political and military leaders. The felony in question is one that has never been tried before and no one has ever been tried internationally – the crime of waging a war of aggression, which at the time was known as a crime against peace.
Some legal scholars and public figures argue that Russia’s leaders should similarly be prosecuted for invading Ukraine. They envisioned a special court with high-profile defendants, including Russian President Vladimir Putin. The court will “signify our determination that the crime of aggression will not be tolerated, and that we will not let anything happen to put an end to the terrible events we are witnessing”. a statement in March by several international lawyers, a former Nuremberg Prosecutor and former Prime Minister of the United Kingdom Gordon Brown.
https://www.wsj.com/articles/the-push-to-prosecute-russias-vladimir-putin-for-the-ukraine-war-11651492870 The Push to Prosecute Russia’s Vladimir Putin for the Ukraine War