As of Thursday morning, the “reasonable chastisement” of a child by a parent is no longer a valid shield against a charge of common assault. Instead, any parent who hits a child faces the same potentially criminal treatment as if the victim had been an adult – whatever the family’s belief or religion.

“The common law defence of reasonable chastisement is unconstitutional and no longer applies in our law,” ordered Johannesburg high court Judge Raylene Keightley, a judgment in which fellow judge Ellem Francis concurred.

Corporal punishment has previously been outlawed as a punishment in the justice system or in schools, but courts have scrupulously steered clear of pronouncing on smacking within the family.

Keightley, however, was blunt about the effect of her order reaching not only into the home, but overruling religious belief.

“The removal of the defence will not prevent religious believers from disciplining their children. It is so that they may have to consider changing their mode of discipline, but in view of the importance of the principle of the best interests of the child, this is a justifiable limitation on the rights of parents,” Keightley said in a lengthy judgment.

“This is a case where I am satisfied that it is permissible to require religious parents who believe in corporal punishment to be expected to obey the secular laws, rather than permitting them to place their religious beliefs above the best interests of their children.”

Keightley said that parents who did hit their children would not be criminally charged “willy nilly”, but would be diverted to existing intervention services. At the same time she found that the state should be “empowered, rather than shackled, by the arsenal at its disposal to investigate, prevent and protect children from harmful and potentially harmful situations”.

The court had been considering an appeal by a man identified as YG against his conviction in a magistrate’s court for assaulting his son and wife. YG said he had caught his 13-year-old son surfing pornography after circumventing their home internet security system. As a religious Muslim man, YG said, he felt it important to teach his son that pornography is wrong.

He assaulted his wife later the same night in what he claimed was self-defence. She is described as weighing between 40 and 50 kilograms.

His son reported YG for assault, and his wife is in the process of divorcing him.

Keightley rejected YG’s defences, saying he had kicked and punched his son in what was “without any doubt” assault, and that his wife had not been the aggressor.

In considering YG’s defence of reasonable chastisement, Keightley asked interested parties to make submissions on reasonable chastisement, and heard arguments from The Children’s Institute, the Quaker Peace Centre, and Sonke Gender Justice, all opposed to corporal punishment. Social development minister Bathabile Dlamini also made a submission strongly in support of removing the defence.

Non-profit organisation Freedom of Religion South Africa (Forsa), which claimed to represent six million religious people, argued to retain the reasonable chastisement defence.

“Forsa explains that its interest in the matter lies in that millions of believers believe that the scriptures command reasonable and appropriate correction of their children,” Keightley summarised the position of the organisation. “Thus, for millions of believers, child correction, including physical chastisement at times, is a central to their faith. They submit that the court has a duty to respect and protect the religious convictions and beliefs of those believers who follow this tenet.”

The defence Forsa fought to retain is sometimes called the moderate chastisement defence or the disciplinary chastisement defence. It protected parents who would, if they meted out the same treatment to an adult, be liable for conviction on common assault, as long as their treatment of their children was reasonable.

The reasonableness of the discipline was measured against the nature of the infraction by the child, the motive of the person punishing, the force used, the object used to punish, and the age, sex and build of the child.

Once a parent raised the defence, the state was obliged to prove that the punishment had exceeded the bounds of reasonableness.

But that offended the Constitution Keightley found, including by making children “second-class citizens” with less protection in law than adults treated in a similar fashion.