Christopher Bellamy: How do you restore order in a society like Iraq?

The spectacle of British soldiers bundling 'Ali Babas' into Warrior vehicles in Basra highlights the problem: what law do you use?

"Peacekeeping is not a job for soldiers, but only soldiers can do it." Never was Dag Hammarskjold's famous remark better illustrated than by events in Basra over the past three days. The rapid switch in the British troops' role in Basra from fighting to law-enforcement is the clearest example yet of what scholars and practitioners of peace-support operations are now calling the "security gap". The gap between soldiers fighting and policemen and policewomen policing.

For the moment, Hammarskjold's paradox certainly holds true. In Basra, the security gap has opened up more sharply and vividly then ever before. The Iraqi regime has evaporated, people who have been repressed for decades and caught in the midst of an untidy war for more than two weeks are, understandably, running amok. British soldiers are suddenly having to dispense justice and restore public order, because there is no one else. Past operations – Bosnia, Kosovo and Afghanistan – should have indicated that this might happen, but where is the international police force and ready-made set of laws that could have been ready to fill the gap? Nowhere, I suspect.

Security is a prerequisite for peace. The military is one component of that. The others are a police force and a system of law, trial and punishment. The creation of a working police and judicial and legal system is cardinal to building peace. Without a valid system of criminal law, no one can feel safe or secure. Without a working system of civil law, no one can do business. Without a legal system, what is a contract worth?

The spectacle of British soldiers bundling "Ali Babas" – alleged thieves identified by the outraged local people – into Warrior fighting vehicles in Basra highlighted a key problem. What law do you use? This problem occurred in Kosovo.

Foreign troops entered the province on 12 June, but it was not until December that the United Nations decided what the law should be. It was largely the law that had applied before, shorn of some of its racist and discriminatory provisions. In the interim, the international force, K-for, conducted arrests, often according to the national law of the various national contingents. It might, therefore, be better to be arrested by the Norwegians than the Turks.

No doubt lawyers somewhere are going through the Iraqi legal codes to try to hammer out laws applicable in the new Iraq. In the interim, it is likely that the British will be using a mixture of military law and common sense. It also puts new responsibilities on the military police, whose traditional role is policing soldiers

In a normal peace operation, the next stage would be the insertion of United Nations Civil Police (Uncivpol), drawn from the police forces of contributing nations. There is a slight problem with Iraq, however. The role of the United Nations in peacebuilding is not defined and may be the subject of violent disagreement. So no UN Civil Police. Furthermore, neither Britain nor the US has a national police force

The Kosovo experience was a salutary lesson. The police were synonymous with the worst aspects of the old regime, as they probably are in Iraq. You cannot bring them back to keep law and order. The same goes for courts and judges You need a new police force and a new judiciary. They are not going to appear in a hurry.

In Kosovo, after the departure of Serbian forces and military uniformed police, the Kosovo Liberation Army (KLA) moved in to fill the space left behind. This caused the international community big problems, because the KLA was not averse to its own brand of retaliatory ethic cleansing.

Policing in the "security gap" requires officers who are skilled in "normal" policing areas, including criminal investigation, but are also armed and able to respond robustly to residual opposition including "spoilers" - people out to destabilise the move to "normality". This is a real problem. It is much easier to employ - and deploy - a battalion of infantry than a battalion equivalent of police. Policemen and women are expensive.

The Chief Constables of the 43 United Kingdom police forces are, understandably, unwilling to release their highly trained and scarce armed response teams to go abroad. The lead in providing civil police to take part in peacekeeping operations has therefore been taken by the two fully armed police forces in the UK: the Ministry of Defence Police (MDP) and the Police Service of Northern Ireland (PSNI), formerly the Royal Ulster Constabulary. Both have been successfully employed in Kosovo. Deployment of "ordinary" policemen and women is, meanwhile co-ordinated, rather quaintly, by the Warwickshire Constabulary.

Equally problematic, however, is creating a fully functional judicial system. There is little use in having even a functioning police force if the rest of the legal system is not up to the job. In Kosovo, detention centres had been destroyed by Nato air strikes and by retreating Serb forces, so makeshift centres were established. When they became full, suspects had to be released. Many trained and impartial judges had fled, and those who remained would probably have been unacceptable to most of the local population. Given the way the Allies have targeted the Iraqi regime and its terror apparatus, the same situation will apply there.

Attempts to set up a generic legal code for application by the international community have encountered many problems with cultural norms. Apart from a general consensus that rape and murder are wrong – although even this is subject to different interpretations – there is little that everyone agrees on.

The best that can be hoped for is probably the intent in the follow-up to the Brahimi report that a UN judiciary be created, which could be implanted into post-conflict situations. The creation of a working judicial system is also part of Lord Ashdown's mission in Bosnia. However, with the UN's role in Iraq unclear, none of this experience can be applied at the moment.

The idea of the security gap has been explored by a few academics, notably the American Mike Dziedzic in Policing the New World Disorder (1998). His model shows a small number of UN civilian police being deployed soon after the military operation starts, building up as the military presence scales down and then training and eventually handing over to local police and judiciary. Once again, however, the insertion of UN Civil Police is crucial in Dziedzic's model, whereas the new rulers of Iraq have not decided how, if at all, they will avail themselves of the UN. Until they do, the British will have to deploy the Bill and the Americans – Beverly Hills Cop?

Even then, in the long term, it is virtually impossible for a foreign police force, dependent on interpreters and on other personnel whose ultimate loyalty may well be to structures outside the force, to police Iraq effectively. It proved that way in Kosovo. But right now, the only authority that can take responsibility for law and order in southern Iraq are the British and US forces. As the colour sergeant tells the young soldier in the film Zulu (1964): "Because you're 'ere, lad. Nobody else."

Christopher Bellamy is professor of military science and doctrine at Cranfield University