Suppose your 14-year-old son is found to have sexually abused your eight-year-old daughter while babysitting.
He is prosecuted and convicted but his sentence is suspended because he is receiving treatment.
He undergoes an eight-month treatment programme. So far as anybody can tell, he never sexually abuses a child again.
Ten years later your son has a qualification in marketing. He is about to get married. You are proud of the way he overcame that other problem and led a decent life.
He gets a job as the marketing and sales manager of a leisure centre. Because the users of the centre include children, the company seeks routine clearance on your son from the Garda.
The word comes back: your son is on the register of convicted child-abusers. The leisure centre tells him not to bother turning up for work and never to set foot on their premises again.
Because your son had begun to frequent the centre when he was preparing for his job interview, the management calls in the staff and warns them to be on the lookout for him. One of the staff knows his girlfriend and tells her what they have learned. She calls off the wedding and ends all contact with him.
Gradually, the word circulates among your friends and neighbours. Remarks are made in the street. The family starts to get threatening phone calls. Your son leaves for England, his life in ruins.
Down the street a paedophile who has never been convicted has a good laugh at it all.
This story isn't all that farfetched. Research quoted in a recent issue of the Irish Journal of Psychology suggests that 36 per cent of child-abusers are under 20 and 21 per cent are under 15.
Among 23 adolescent sex offenders who completed a treatment programme at the Northside Inter-Agency Project in Dublin the average age at which they committed their first known offence was 14 and the average age of the victims was eight.
The project considers most of those who complete the treatment programme to be at low risk of reoffending.
Should they be on the register for the rest of their lives? Some would say they should, on the grounds that they might reoffend, that they can never be sure. Others would say that to keep them on the register permanently is unfair in itself and takes away the incentive to go through a tough treatment programme.
A register of sex offenders is not a simple thing to devise. This is why it is important to give the Minister for Justice the time to get it right.
It makes sense that such a register, maintained by the i, Garda, would be of benefit to bodies employing people working with children. Such bodies would include health boards, schools and sports organisations.
Failure to keep one's current address up to date on the register could be made a criminal offence: so if a paedophile, for instance, was found to have got himself into a job where he had contact with children, he could be jailed for failing to keep the register up to date, even if there was no forensic evidence that he had abused children in the new job.
But should it only be paedophiles on the register? Men who abuse boys outside their own families are among the most likely reoffenders of all.
But it can be argued that most men who abuse children are not paedophiles. They are not fixated on children, but they abuse them nonetheless.
Among this group the rate of reoffending seems far lower than for paedophiles. But the fear of being listed on a register might well act as a deterrent. And the prospect of getting off the register after, say, seven to 10 years free of convictions could give them a powerful incentive to co-operate with treatment programmes.
But that only works if we have the treatment programmes. There is only one small specialised treatment programme in the prisons. There is no more than a handful of treatment programmes in the community.
It is treatment, and not a register, which offers the best hope of cutting down on reoffending.
So while a register makes sense from the point of view of schools, sports organisations and others, to be truly effective it must be accompanied by greater investment in treatment programmes, in the prisons and outside.