The current debate surrounding the right of parents and caregivers to spank their children begs the question of whether corporal punishment actually works.

Most Canadian parents obviously believe it does, because surveys across the nation continue to show that the vast majority of parents resort to spanking when their instructions meet with failure or resistance.

Clearly, then, Canadian parents are finding that spanking succeeds in starting or stopping whatever it is about their kids that bugs them.

But they are right only to a limited extent and then only in the very short term.

In a nutshell, the available research evidence shows that parenting practices such as spanking, shouting, and physically removing a child can be very effective at influencing a young child's behaviour in the short term.

To be more precise, what punishment does best is stop kids from doing things here and now.

If you want to stop a toddler from sticking a fork into the power outlet, for example, or from running onto the road to chase the cat, spanking will probably do that for you.

The trouble is that short-term compliance like this is about all that spanking is good for.

Paradoxically, harsh punishment actually interferes with longer-term rule-learning because kids are too fearful or too traumatized to learn much at all.

If you don't believe that, just try boning up on your French grammar while someone electrocutes you every time you make a mistake.

To put this another way, the effect of physical punishment is to inhibit behaviour in the short term, not to impart generalizable norms or principles that children can carry from one situation to the next.

More than this, we know that harsh corporal punishment is associated with aggression and anti-social behaviour against other children at school.

This is partly explained by the finding that impulse control (the ability to delay our needs and urges) is actually lower for children whose parents rely primarily on physical punishment than it is for those whose parents occasionally or never resort to corporal punishment.

Research on domestic violence has also revealed a close link between corporal punishment in childhood and physical abusiveness later in life.

It is clear, for example, that spouses who experienced frequent corporal punishment (monthly to daily) during childhood also have a higher rate of assaulting a partner than those who were not hit as a child.

This link between corporal punishment and partner abuse later in life holds irrespective of whether the punishing parent was a father or a mother.

Given this research evidence and the fact that boys are more often subjected to physical punishment than girls are, it is hardly surprising that men are also more likely to be convicted of violent offences than women are.

Indeed, the strength and consistency of this link between corporal punishment and domestic violence later in life suggests that the most effective long-term strategy for preventing violence against women would actually be to end harsh corporal punishment against boys.

You will note that I have continued to employ the descriptor "harsh" when applied to corporal punishment.

This is because the clearest research evidence we have refers to acts like hitting with a belt or brush, and slapping or punching in the face.

Fortunately, most Canadian parents do not resort to such tactics (though an alarming number do), but this does not mean that milder forms of corporal punishment are without ill effects.

Only that milder corporal punishment is likely to produce milder negative consequences.

All of this does not mean, of course, that children can or should be raised without aversive parenting of any kind.

The imposition of authority against the child's will is developmentally appropriate during the early years of a child's life in particular.

But the problem with last Friday's court ruling is that it effectively says that a little bit of violence is okay when our courts would serve us better if they told us that any form of violence is always an expression of failure to carry the day by reasoned and peaceful means.

Jim Barber is dean of the Faculty of Social Work at the University of Toronto. His latest book, Children In Foster Care (Routledge, 2004) chronicles the lives of children who are removed from homes in which they were found to be unsafe.