But now it is on the verge of reality. Delegates from more than 120 countries gather in Rome today to finalise a treaty setting up a permanent International Criminal Court under the aegis of the UN.
The 175-page draft they will pore over has been four years in the making. At least five more weeks of gruelling negotiation lie ahead, pitting supranational idealism against the dictates of raison d'etat.
But at the end of this uniquely violent century, the world has its best ever chance to set up an effective independent mechanism to deal with the perpetrators of war crimes, genocide and crimes against humanity. Whether it will take it is another matter.
On so complex an issue, agreement was never going to be simple. The nuances of opinion are almost infinite. But three broad camps of opinion have emerged. Ostensibly, the distinctions between them are legal. In truth, however, they are utterly political, and quite possibly irreconcilable.
One group, with India, Mexico and Egypt in the forefront, would sooner have no court at all. Another, led by the United States, China and France, wants an ICC, but one that is firmly subordinate to the UN Security Council. The third and largest grouping is of so-called "like-minded" countries. It favours a strong court, and in its mix of Europe, Canada, and small- and medium-sized developing states it resembles the coalition behind the 1997 anti-landmine treaty.
The main points of argument are four. The first is state consent. A genuinely powerful court would be able to initiate its own prosecutions. France, however, argues that a suspect's own country must first agree, a condition that surely would emasculate it from the outset. Would an Iraqi government consent to the indictment of Saddam Hussein? Flowing from this is a second dispute, over the precise powers of the prosecutors. Too much, says the US, and "rogue" prosecutors would be able to pursue vendettas by launching frivolous cases against Washington and its peacekeepers around the world.
A third bone of contention is the balance between the ICC and national courts. Obviously suspected criminals should be tried if possible in his own country and its laws. But precisely how is it to be determined when a national judicial system is either unable, or unwilling, to act?
But the biggest disagreement surrounds the ICC's relationship with the Security Council. The US and most other major powers insist that any prosecution must first be authorised by the Council. For advocates of a strong court, this is tantamount to a kiss of death, giving the five permanent members the right of veto. Or rather, four. This time Britain is on the side of the angels - ready to forgo its veto rights in the higher interest of an independent court.
Few of the objections stand up to serious scrutiny. If peacekeepers have committed war crimes, they should clearly be punished, whatever their nationality. And as My Lai showed, America is capable of trying such crimes by its own servicemen. As for rogue prosecutors, everyone agrees that their decisions should be subject to approval by a panel of judges.
A more serious complaint is that an unfettered court might interfere with delicate peace-making efforts by the Security Council. But not necessarily. As Bosnia demonstrated, the 1995 Dayton accords were signed despite explicit provision that war charges could still be brought against the likes of the Bosnian Serb leader Radovan Karadzic.
In reality, America's attitude to the ICC reflects its ambiguity to the United Nations as a whole. The reservations of France and China, among others, are born of recent practical experience. Prime candidates for the attentions of the ICC would have been the Hutu rulers of Rwanda, and Pol Pot. Paris in the first instance, Peking in the second, might have had some embarrassing complicities to explain at any trial.
So, is the game worth the candle? The deterrent effect of an international court is unproven, it may be said. Neither of the present ad hoc tribunals, dealing with the former Yugoslavia and Rwanda have achieved great things.
But such exercises do have a value. Whatever the failings of "victors' justice" at Nuremberg, few would argue that the leading Nazis should not have been put on trial.
Human rights groups accept that some compromise in Rome is inevitable if an ICC is to be created. Too much compromise however, and rather than a weak and over-politicised creature, they would prefer no court at all.