Today's (1 September 2012) 15th anniversary of the introduction of the sex offender register brings a surprise present for the very people it was designed to control - and a nasty surprise for anyone with the protection of children at heart.

From today, paedophiles and other criminals who have committed serious sex crimes will be able to appeal against having their names on the register for life.

The Supreme Court has ruled that if a sex offender, including those whose victims were children, has not re-offended for 15 years they can appeal to be taken off the register At a stroke this could make them almost invisible to the authorities whose job is to track them and ensure they do not commit further offences, such as sexual assaults on children or hoarding vast libraries of sickening child abuse images. In effect their dangerous pasts would disappear from view, potentially leaving them free to search for more young victims, both at home and abroad.

But what guarantee is there that they will not abuse again? It is dangerous to rely on re-conviction rates to assess whether a sex offender is still a risk to children. How can we be sure they have not re-offended - maybe they just have not been caught again? And who is to say they will not harm a child again once they are free from the restrictions imposed by the register? In fact, the great majority of child sexual abuse never comes to light and is never prosecuted as the young victims are often too scared to speak out.

Though we understand this legal ruling cannot be overturned, the NSPCC's view is that we can never be sure a sex offender will not re-offend. There is no known 'cure' for adults who sexually abuse children. We can only try to control and contain their behaviour which is why they should stay on the sex offender register for life.

Sex offenders are sophisticated predators. They are manipulative and will often go to great lengths to get close to their potential victims. Some will have abused children many times before they are caught. This is why it is so important that they are closely tracked after their release as there will always be a risk they will abuse again.

Not all child sex offenders receive therapy to address their abusive behaviour and even with those that do, there is no guarantee it will stop them abusing children again, sometimes many years later.

The best way to protect children from known sex offenders is a combination of treatment for offenders in prison. And for the police, and in some cases the probation service, to monitor their movements when they are released into the community. However, we must remember, not all sex offenders have been, or are ever, convicted so it is still vital that the public also take responsibility for protecting children in their community by reporting any concerns to the authorities or the NSPCC.

The UK is only one of four European countries to have a sex offender register and it has made a great contribution to child protection in this country. Nobody is claiming that the register is a silver bullet, but it is still an important weapon in the fight against child abuse. Not only does it help keep paedophiles away from children, it has also increased public understanding and awareness about the way sex offenders operate and the risks they pose.

So even if sex offenders now have the legal right to appeal against being on the register, it is hard to envisage in what cases a successful appeal could be justified. Without undeniable evidence they are no longer a danger to children, surely taking them off the register after such serious offences is too great a risk for society to take. We must never forget how physical and emotional harm from sexual abuse can damage children's lives. The NSPCC believes that justice and protection for children should come above the civil liberties of a convicted sex offender who clearly had no regard for a child's right to be protected from abuse.

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