"RUC 1922-99 Rot In Hell". If those words, scrawled on a Belfast gable wall, turn out to be prophetic, it will not just be Northern unionists who will not sleep soundly at night. Cheap cracks at the RUC and calls for radical change from an ardfheis platform ignore the South's vital interest in maintaining an effective RUC in Northern Ireland.

Imagine you live in west Belfast. You are a Catholic. You feel Catholics have had a hard time over the years. You would like to see Ireland united. You hope the peace process will mean more jobs for west Belfast.

The trouble is young Sean has come home from school and told you his teacher has been doing things he shouldn't. You suspect sexual abuse. You ring the police. A pleasant young RUC woman calls, takes down all the details and promises everything will be done to investigate the allegations. She says not to worry; she will contact social services and see that Sean gets all the counselling he needs. The next day, the teacher is suspended.

You fool! Your MP is Gerry Adams. Did you not hear that your duty was to walk around to the nearest Sinn Fein advice centre and report to them? Their team of trained sexual abuse experts is ready to deal with it.

OK, so they are not exactly experts, as such. But, surely anything is better than collaborating with the RUC, an unacceptable police force?

What is the point of your local councillors putting on a re-enactment of the Salem witch trials for the benefit of Chris Patten if ordinary nationalists start ringing the RUC? How can the defenders of the Catholic people hope to bring about a 32-county democratic socialist republic, then? Bobby Sands did not die for a cross-Border trade body. If we can keep the guns as a wee reminder to the Brits if they don't deliver and if we can get Patten to scrap the RUC there could be a united Ireland in, say, 15 or 20 years. For heaven's sake, your Sean will get over it.

The problem for Gerry Adams is that too many Catholics are more prepared to put their faith in the RUC and British justice than in the IRA and summary justice. According to the latest statistics produced by the Police Authority, 65 per cent of Catholics thought the RUC's performance was very good or fairly good and only 15 per cent of Catholics think it is doing a poor or very poor job.

Most interestingly, when Catholics are asked if the RUC treats the two traditions equally, 50 per cent say their own local experience is that they do but only 37 per cent perceive that is the case generally. The Sinn Fein machine is clearly having an effect. Some Catholics even believe the RUC treats Catholics better than Protestants and nearly half of Catholics, as well as 89 per cent of Protestants, are opposed to even a change in the name of the RUC.

So much for the RUC being an unacceptable police force to nationalists. Sinn Fein spokesmen regularly trot out their favourite line that the RUC is "the most discredited police force in western Europe". It is certainly the most vilified police force in western Europe. Not surprisingly, complaints come in the main from those with a vested interest in dismantling the thin green line between legitimate political activism and terrorism.

The endless show trials Chris Patten has to sit through in republican areas do not seem to focus on the RUC's record on sexual abuse, burglary or car crime. No, complaints only seem to be in relation to the RUC's anti-terrorist role. Why is it that at the public meetings in the republican heartlands, no person has stood up and said his or her child was sexually abused, they rang the RUC and the perpetrator is now behind bars? Not because the example above is a fantasy but because no person would dare. Certainly not if he or she had ideas about continuing to live in an area where the IRA has sway.

The Provisional movement's problems are not confined to situations where ordinary nationalists report sexual or domestic crimes to the RUC. As recently as 1997 the IRA had to issue a statement in west Belfast warning the local Catholic population that their willingness to co-operate with the RUC in their efforts to stem terrorism in all its forms, including "punishment" attacks, was frustrating their ends.

For citizens of the Republic, all this can seem remote; something for Chris Patten and the local politicians to sort out. As far as the Southern State is concerned, it is irrelevant. The Garda Siochana's authority and acceptability as a police force is unquestioned. The tendency is just to be thankful the gardai are not like the RUC if the stories to be heard from nationalists in the North are to be believed. If citizens of the Republic were to adopt such an attitude, they would be doing so at their gravest peril. It would be a dereliction of duty to the Irish State.

Sadly, the belief that all are equally guilty for what has happened over the last 30 years has permeated even the higher echelons of government in the Republic. For the record, republican terrorists have murdered nearly 2,000 people and loyalists over 800. By contrast, the RUC has killed just 51 and had six times that number murdered from its own ranks. All 51 of those cases have been the subject of the most vigorous investigation and report to the Director of Public Prosecutions where warranted. If only the same could be said in relation to the nearly 3,000 terrorist murders. Only a quarter of republican murders and a half of loyalist murders have resulted in convictions.

What the people of the Republic must ask themselves is: why has there been no major attack in the 26 counties since the savagery of the UVF's Dublin and Monaghan bombings in 1974? Was it because of benevolence on the part of loyalist paramilitaries or was it because the RUC worked tirelessly to infiltrate the paramilitary sects and ensure any such action in the future was frustrated?

Not only has the RUC been in the front line of insulating the Republic from the worst effects of loyalist terrorism and of scuppering the IRA's plans to "take power in Ireland", but it does a thankless job tackling gang criminality. What would be the effects on Southern business and tourism if the terrorist factions, reincarnated as a criminal mafia, were met only by a Northern Ireland Police Service with one arm tied behind its back? Would the Celtic Tiger roar then?

"The RUC. A force for Ireland. A force for good." should be engraved on the heart of any true Irish democrat. Sacrificing it for the expediencies of the peace process would be folly. Remember Sicily. Don't say you weren't warned.

Steven King is an adviser to the UUP Deputy Leader, Mr John Taylor.