The Government is taking a drastic step in making witnesses to parental child abuse criminally liable if they do not report the abuse to the authorities. In many cases the witnesses will be close relatives or good friends. It is easy to say that no decent friend or relative would turn a blind eye to brutal treatment of an infant but it is asking a lot of anyone to come between a parent and a child. That, however, is exactly the reason the law should require it.

Among those who criticise the proposed law, Green Party co-leader Metiria Turei thinks it would be better to support those who are in a position to report abuse, not threaten them with a criminal charge that will carry a possible 10 years' jail. Yet that may be the best form of support these people could possibly be given.

Concerned relatives or close friends would no longer face a conflict between their loyalty to the parent or carer and their concern for the child. Their risk and the possible penalty they face would be clear to them and, just as important, to the abuser. Both parties would know the witness has no choice. If that deters abuse within sight of such witnesses, it would be a good thing, reducing the incidence of abuse if not its severity.

Of course it will remain necessary for the police to prove the abuse was witnessed, and that could often be difficult. Police concentration will be on proving the guilt of the primary offender, not that of bystanders. This is one of those laws that cannot rely on enforcement to be effective. Its existence must be made known powerfully and the authorities should not be afraid to prosecute relatives for keeping quiet.

The proposed law has been prompted by the Kahui case, in which the 3-month-old twins died of severe head injuries and the family closed ranks. The law will apply to adults who do not necessarily live in the house where the abuse is occurring, but are closely connected to the household. They will be obliged to take steps to protect a child they know to be at risk of physical abuse, sexual assault or death.

The bill introduced by Justice Minister Simon Power is not the only Government response to child abuse of late. Social Development Minister Paula Bennett has announced a green paper on the subject. It suggests ways that schools and social agencies can share information about children in risky situations.

The day her discussion paper was issued a woman was committed for trial for the abuse of her 9-year-old daughter. The case had come to the attention of 12 welfare agencies and has been the subject of a ministerial inquiry into their handling of it. Ms Bennett said it had not prompted her green paper but the recital of alleged offences against the girl is enough to make the case one of the more serious to come before New Zealand courts.

A country of our population is too small and intimate for parental child abuse to be as serious as it seems to be. No child's misbehaviour warrants a violent response. Too often the parents plainly lack the maturity to be entrusted with the care of an infant. Doctors and hospitals should be the first to raise concerns about the parents' competence when they see suspicious injuries or a lack of care.

Police and welfare agencies should not hesitate to remove such children, preferably into the care of responsible relatives but into foster homes if necessary. The "whanau-first" principle espoused in Ms Bennett's paper is a good one as long as her colleague and Maori Party leader Tariana Turia can make it work. But cultural needs are not the most urgent for a child at risk of injury or death.

There is no greater shame in this country than the maiming of children. Drastic steps are required.