Brendan Simms: If Britain had had its way, Karadzic would be a free man now

Doing deals with war criminals is not only wrong but bad realpolitik. It's a lesson that applies to Darfur

The capture of Radovan Karadzic, and his prospective extradition to face the war crimes tribunal at The Hague, comes in the nick of time. It boosts the credibility of the indictment recently issued against the Sudanese President, Omar al-Bashir, for his alleged complicity in the genocide in Darfur.

Moreover, it is now difficult to argue that the court is biased against Muslims, given that one of those jointly responsible for the greatest massacre of Muslims in modern times – in Bosnia between 1992 and 1995 – has been apprehended. The arrest is also a boost for The Hague tribunal itself, which had been under fire for procedures so cumbersome that its star prisoner, Slobodan Milosevic, died five years after he was arraigned, but before judgment could be pronounced.

Today the pursuit of Karadzic and the Bosnian Serb military leader, Ratko Mladic, who remains at large, seems uncontroversial. So it is worth remembering that the creation of the tribunal was furiously contested at the time. At almost every stage of its gestation at the United Nations in 1992-1993, British officials tried to stifle it at birth. For example, when the United Nations Security Council established a commission to investigate breaches of humanitarian law in the former Yugoslavia in October 1992, Britain successfully opposed a demand by the US State Department to call the body a War Crimes Commission.

Britain also resisted supplying the commission with evidence from debriefed former camp detainees who had found refuge in the United Kingdom. In particular, British diplomats and advisers jibbed at revoking the customary immunity for heads of states, in this case Serbian president Milosevic, who was responsible for orchestrating most of the crimes. As Frits Kalshoven, the Dutch head of the Geneva Commission on war crimes, subsequently remarked: "Britain hasn't done anything for us – nothing at all."

British officials tried to sabotage the tribunal because they genuinely believed that the pursuit of international justice would interfere with the messy business of negotiating a settlement between the "warring parties". In particular, the proposed war crimes tribunal cut across the ingrained belief of Douglas Hurd's Foreign Office that while Milosevic and the Bosnian Serb leaders were the problem, they must also be "part of the solution". As Douglas Hogg, the minister of state in the Foreign Office, told the House of Commons in February 1993: "If the authority – the responsibility – for those crimes goes as high as the honourable gentleman ... I expect, we must ask ourselves what is the priority: is it to bring people to trial or to make peace?"

Indeed, one senior British diplomat at the British mission to the UN Security Council at the time recalled that there was "a general feeling that at some stage we were going to have to talk to the Serbs. It wasn't going to help very much if all of them were going to be in fear of arrest at The Hague."

Britain ultimately lost the battle against military intervention to stop the ethnic cleansing, but some sort of "realist" trade-off between peace and justice took place in the negotiations leading to the 1995 Dayton agreement. There may not have been an explicit deal, but there was certainly an implicit understanding that Milosevic would not be prosecuted. Otherwise, his cavalier recognition of the tribunal then, and his subsequently unfulfilled promise to deliver indicted war criminals to The Hague, made no sense. One way or the other, the practical immunity extended to Milosevic then left the real problem unaddressed, as events in Kosovo shortly after proved.

More recently, the realpolitik argument has been advanced against the indictment of Bashir, which some fear will drive the Sudanese government ever more into a corner, endanger the peace agreement between the Khartoum government and the southern rebels, and even stifle negotiations over Darfur.

It all reminds one of John Cornford's famous study of academic politics in which he observed that there was only ever one good reason for doing something, but 10 reasons for not doing it. In fact, the history of such tribunals suggests the exact opposite. When the indictments against Karadzic and Mladic were finally issued in 1995, after three years of war, it helped to convince Belgrade to pull the rug from under the Bosnian Serb leadership. When the long-overdue indictment against Milosevic himself was produced in 1999, it played a part in persuading the Serb leader to end the Kosovo war before it was too late. And although it is early days yet, the shot across Bashir's bows has produced not the explosive reaction Khartoum blustered about in advance, but a very much more measured tone on their part. In these cases, realpolitik and international justice have proved to be complementary, not contradictory.

The real tension between justice and pragmatism lies elsewhere. It is well known that the United States, which supported ad hoc tribunals for Rwanda and the former Yugoslavia, has refused to sign up to the International Criminal Court with a universal remit.

What is often overlooked, however, is the fact that without the Americans, The Hague tribunal would never have got off the ground; the Bosnian Serbs would not have been defeated in 1995, and the international coalition would not have prevailed over Milosevic in Kosovo. The latter operation was launched – let us not forget – without an explicit United Nations mandate. Humanitarian intervention and international justice thus depend on a large degree of – often unilateral – US military assertiveness. An international criminal court that places American commanders at the mercy of the human rights lawyers would strangle any US appetite to take on the real human rights abusers.

If the purists get their way, we shall have a transparent system of international justice, based on universal principles, but no defendants, no convictions and consequently no justice at all. In the quest for a fair and stable international order, the best is often the enemy of the good.

Brendan Simms is a Reader at the Centre for International Studies, the University of Cambridge, and author of 'Unfinest Hour: Britain and the Destruction of Bosnia' (Penguin)