Cambodia is about to pass a landmark treaty which will make it possible to try some of those responsible for Khmer Rouge atrocities, writes Jonathan Power.
'The moral arm of the universe is long," Martin Luther King once said in one of his memorable speeches. "It bends towards justice".
But it is doubtful if the people of Cambodia, the site of the original "Killing Fields", feel that this is likely. Yet their understandable cynicism may about to be confounded.
Cambodia's National Assembly is poised to approve a government decision to ratify a treaty, over a decade in the making, that will empower a special court to try surviving leaders of the Khmer Rouge, the communist movement that was seized with a mission to refashion the social and economic structure of its country by the sword and the bullet.
Cambodia incarnates the worst horrors of being caught in the crossfire of wars. It was heavily bombed in secret by the Nixon administration.
Then, when the Vietnamese invaded in 1979, Washington had the audacity to line up world opinion behind recognition of the defeated Khmer Rouge regime.
The incongruous sight of the Khmer Rouge flag flying outside UN headquarters in New York was the most revolting testament to mass murder imaginable.
Finally, by the diligence of exiles and the UN, a kind of incipient democracy was created in Cambodia, and gradually the government has come round to some sort of public trial of a small cadre of the Khmer Rouge's top leaders. Most of the judges will be Cambodian, but there will be one UN-appointed judge and one UN-appointed prosecutor. No conviction or acquittal is possible without their acquiescence.
This is the least intrusive of all international set-ups in an era that has seen in quick succession the creation of UN war crimes tribunals for ex-Yugoslavia, Rwanda and Sierra Leone, plus the establishment of a permanent International Criminal Court to deal with future war crimes.
It would seem, despite the hostility of the Bush administration (and also the governments of Russia, China and India) to the ICC, that the overall world tide is flowing in the direction Martin Luther King said was inevitable.
But there is an influential number of people who see it otherwise. In a recent issue of Harvard University's quarterly, International Security, Jack Snyder and Leslie Vinjamuri argue that "justice does not lead, it follows". In other words, the human rights activists who have fought for these courts have it backwards.
First, the authors say, you need a peaceful political order and then one can start to worry about justice. Only when a government is at peace with its electorate, and can govern without challenge, can it be the right time to introduce norms and laws that will prevent future atrocities.
Thus for them, the Yugoslavian and Rwandan courts have been counterproductive, keeping chauvinistic feelings among the Serbs and Hutus inflamed.
Although they do not spell it out, presumably they think the slow, tortoise-like approach of the Cambodian government has been the right one.
There is some truth on the authors' side. The Milosevic trial has been allowed to continue too long for it to produce quick therapy for a country still seized by the sanctity of its cause. The boil has not been lanced.
Indeed, one can go further and say it is difficult at the moment to argue that these courts have had a measurable deterrent effect on new would-be war criminals.
They still seem to thrive, as events in the Congo, Sudan, Afghanistan, Guatemala, and, on a smaller scale, in Assam suggest.
Don't the leaders of these ongoing atrocities read the writing on the international wall? Obviously not.
But the argument misses two important points. We do not in civilised countries have criminal justice systems that are capable of deterring all criminals. Deterrence only works at the margins.
We seek justice in the courts partly to punish, partly to uphold a standard, and partly in the hope that those punished will reflect on their crimes and resolve to put their past behind them.
It is the same in the international arena. We can hope that some villains and governments may be deterred, but we should not count on it. Politicians like Pol Pot and Milosevic who decide on ethnic cleansing have all calculated the odds and decided, albeit mistakenly, that they will win through.
Nevertheless, a standard is defined. In contemporary history it reaches back to the Nuremberg trial. Now it is being reinvigorated by the international courts. Over time, over generations, new standards of justice do develop.
That is why black people are no longer lynched in America and South Africa, why democracy has spread so rapidly in the last 20 years and why, according to the Stockholm International Peace Research Institute, the number of violent conflicts in the world has fallen steadily each year of the last decade.
Martin Luther King was right.