Where is international justice when this Iraqi war criminal is given amnesty?

We must assume that to become the head of armed services under Saddam one needed to develop a certain moral ambivalence

It was one of those stories that just slithered by. There is so much happening in Iraq these days one can almost see how. Almost. Iraq's former minister of defence, Sultan Hashim Ahmed, surrenders to American troops and is taken into custody. Then it is announced that he is to be granted immunity from prosecution. We are assured that Sultan Hashim Ahmed isn't the worst of Saddam's coterie, a second- or even third-rate brute. Given the competition from the likes of "Chemical" Ali or Saddam's own sons it is hard to be sure what level of cruelty and ruthlessness the now surrendered minister of defence possessed. He was evidently not a man who enjoyed feeding people into shredding machines, but where exactly did he draw the line in his willingness to enforce the will of Saddam? We must assume that to become the head of the armed forces under Saddam one needed to develop a certain ambivalence in matters of personal conscience.

We know that deserters from the army he commanded had their ears lopped off. Indeed, the British administrators in southern Iraq are now encountering a regular flow of such people seeking compensation. It is also reported that Sultan Hashim Ahmed, as deputy chief of staff of the Iraqi army, persuaded General Norman Schwarzkopf to allow Iraqi forces to use their helicopters in the no-fly zone following the retreat from Kuwait in 1991. Just a month later those same helicopters were being used to slaughter the Shia of the south and the Kurds in the north. As I say, compared to Qusay the shredder of men and his psychopathic brother Uday it is tempting to regard the general as hardly much more than a fat lump of minor unpleasantness.

But I would like to know what his precise role was during the Iraqi invasion of Kuwait in 1991. Then he was deputy chief of staff of an army which raped, pillaged and slaughtered to its heart's content. The same army abducted 600 Kuwaitis and took them to the torture cells of Saddam's Iraq. They haven't been seen since. In Kuwait itself there were at least 1,000 documented cases of rape by troops who also had orders from above to use flame throwers, machine guns and grenade launchers against civilian demonstrators. Nor should we forget the environmental catastrophe unleashed when the retreating army blew up 723 oil wells. Perhaps at the very least we would be helped by a public description of the qualities required to climb so high in the Iraqi army.

A voice of caution whispers in my ear. Isn't it a little unfair to blame any of the Kuwait nastiness on Sultan Hashim Ahmed? I won't bore you with a dissertation on the laws of command responsibility and the obligations of commanders of occupying armies, nor will I speculate about what his role was in those crucial months of 1990-91. Why I'll even forgo the temptation to ask exactly what he did when the Iraqi military rampaged around Basra and the Kurdish north. The straightforward answer is that most of the slaughter was carried out by the Republican guard who operated under a separate command. But Lt Gen Ahmed cannot have missed what was going on. (Now there was a moment to call up Norman Schwarzkopf and say: "Listen, Norm, I want out. This horror sickens me. I want to come over and tell you all I know about some terrible weapons of mass destruction.") Yet I am willing to set all that to one side for the moment. I will even agree with you and say: "Yes, let us give him the benefit of the doubt. Let us assume innocence until his guilt is proven before a court of law."

But here is the nub of the issue. We'll never know, one way or another. For the minister of defence has been granted immunity from prosecution. To secure the surrender of Sultan Hashim Ahmed the US commander in northern Iraq, Major General David Petraeus, put his name to one of the most extraordinary letters ever written by a military man.

Among other things he promised to treat Hashim Ahmed with the "honour and dignity befitting a General officer". (The boys running around with only one ear down in Basra would have something to say about that.) "As military men we follow the orders of our superiors," wrote Gen Petraeus. "We understand the unity of command and supporting [sic] our leaders in a common and just cause." Let's take that sentence in two parts. That old line about "following the orders of our superiors" is a justification that won't go too far in a modern human rights court. And to which "common and just cause" was the American general referring?

It cannot have been the systematic and continuous abuse of human rights for which Saddam's regime was justly infamous. After all, only this week we heard the Foreign Secretary, Jack Straw retrospectively argue the case for the war by saying that it had brought this reign of terror to an end. Last January when the Government presented its dossier on human rights abuse in Iraq, the Foreign Secretary said people needed to understand "the comprehensive evil that is Saddam Hussein". President George Bush uses almost every public speech to talk about the liberation of the Iraqi people from gross human rights abuse. That is true. The war did empty the prisons and torture chambers.

But there is an intellectual and moral inconsistency here. If you believed the scale of human rights abuse to be so great as to provide at least a partial justification for war, why would you settle for anything less than a full exposition of the truth? Getting rid of the regime, as Bush has acknowledged, was only to be the first part of tackling the human rights disaster in Iraq. The next step should be trials and truth-telling.

As I've conceded, Sultan Hashim Ahmed may not have been the worst of perpetrators, but until a few days ago he was number 27 on America's list of wanted regime villains. That at least suggests he has a case to answer for human rights abuses. But by granting him immunity the Iraqi people have been robbed of the chance to know what part he played in their oppression. By what right, they might ask, does an American general usurp the function of a judge?

There are plenty of precedents for this. All kinds of deals have been cut that allow accused villains to escape justice. Recently the US helped to supervise a deal which allowed West Africa's number one monster, Charles Taylor, to retire in luxury to Nigeria. What made that deal unique was that Taylor was the subject of an indictment by the UN Special Court for Sierra Leone. The court accused him of having "the greatest responsibility for war crimes" in the region.

A few years ago I had high hopes for the evolution of international justice. With courts investigating genocide in the Balkans and Rwanda it seemed a new order was being born. I no longer have high hopes. In fact after Taylor and the events of the past week I don't have hopes at all. The logic in the cases of Taylor and Hashim Ahmed is that by giving them a deal you prevent further bloodshed. But by cutting such deals we simply entrench a culture of impunity. The victims are left with their pain. The dictators and torturers of the future are reassured.

The writer is a BBC Special Correspondent