Smacking of children is a deterrent similar to electric fences being used to keep animals in a field, the Court of Appeal has heard.

Lawyers for Northern Ireland Children’s Commissioner Patricia Lewsley yesterday drew the comparison during a renewed attempt to ban the form of discipline.

Even though legislation allows parents to physically chastise their children, they argued it involved illegitimate violence and physical or psychological pain.

The Commissioner is appealing a ruling that the Secretary of State did not act illegally by bringing the law in Northern Ireland into line with England and Wales.

Mary Higgins QC, for Ms Lewsley, argued that youngsters have protection from torture or degrading treatment under the UN Convention on the Rights of the Child.

As the barrister opened the two-day hearing, Lord Chief Justice Sir Brian Kerr put it to her that some regarded physical chastisement as a parent’s way of showing disapproval.

But Ms Higgins insisted that even without the hurt usually involved, it has a negative impact.

She said: “It’s saying to the child this is a deterrent. If you do X or Y then you’re going to get a little bit of pain.

“It’s not merely disapproval. It’s actually along the same lines as bringing electric fencing around a patch with horses.”

Ms Higgins pointed out that if the animals went too close to the fence they would get a shock.

Referring to research used to strengthen her claims about the impact of smacking on a child, Ms Higgins added: “Whether it’s hurt or not it does shame them. Therefore a negative psychological, if not physical, hurt is associated with smacking.”

Taking an example of a child throwing a tantrum as they are being strapped into a car seat for their own safety, Lord Justice Girvan questioned whether a smack which causes shock but calms them down was, in Ms Higgins view, illegitimate violence.

“In our case it is,” the barrister replied.

Ms Higgins argued that all forms of physical violence were contrary to Article 3 of the European Convention on Human Rights — the right to freedom from inhuman or degrading treatment or punishment.

Pressing her further, Sir Brian asked: “Are you suggesting that if the state becomes aware that there is a prevalence among parents to administer violence to their children which is well beyond reasonable chastisement, on that account the state has an obligation to ban all forms of violence?”

Ms Higgins told the judges that would be a reasonable preventative measure.

She disputed a suggestion that practices such as putting children on a so-called naughty stair caused humiliation. Outside the court Ms Lewsley insisted that the original judgment, delivered in December 2007, breached children’s basic right to be protected from harm.

She said: “I would be failing in my duty to safeguard the rights and best interests of the 500,000 children and young people that I represent if I had not challenged the ruling.”