A survey indicates there has been an increase in the number of parents who choose not to smack their children, in line with the controversial "anti-smacking law" implemented in 2007.
The survey was commissioned by conservative lobby group Family First from Curia Market Research, a firm headed by centre-right blogger David Farrar.
It is based on responses from 500 parents of children aged less than 12. It found that 44 per cent reported never smacking their children since the 2007 legislative change to remove the Crimes Act defence of "reasonable ... force" for parents who hit their children to correct them.
Twenty-nine per cent told Curia they had smacked rarely since the change, 21 per cent said occasionally, 1 per cent said frequently and 5 per cent were unsure or refused to answer.
The never-smacked figure was higher than found in a 2009 Herald-DigiPoll survey of parents of 4-year-olds.
That poll found that 39 per cent of mothers and 33 per cent of fathers never smacked - and that was more than three-fold higher than the rate during the four decades to 1997.
Family First national director Bob McCoskrie said the independent poll by Curia found that parents were "flouting the anti-smacking law, and will continue to do so, despite risking prosecution".
"The research shows that parents are continuing to use smacking sparingly but when warranted - because it works."
But the findings have been interpreted differently by Children's Commissioner Russell Wills, a paediatrician, and unemployment and welfare issues campaigner Sue Bradford, the former Green MP who introduced the law change.
Ms Bradford said: "I'm really heartened by the survey saying that since the law change, 44 per cent hadn't hit their children. If that's true, that's fantastic."
Dr Wills said: "The striking thing about that data is the large number of parents who never hit their children or do so only very rarely.
"It suggests to me that large numbers of New Zealand parents are avoiding hitting their children and that's consistent with my experience clinically.
"Since the law was changed there has been a sharp increase in parents self-reporting to social services for help with their parenting. There has been a substantial increase in parents attending parenting courses that provide alternatives to hitting and are much more effective.
"I think all that shows that New Zealand parents understand that hitting is an ineffective way of disciplining children and they are looking for alternatives."
Mr McCoskrie said the law change had "criminalised an act of parenting which the parents themselves simply don't equate as a criminal act. Parents are treating the law with contempt".
He repeated his call to reinstate the parental defence of reasonable force for correction, but limited to light smacking that caused only transitory or trifling discomfort.
He said police statistics showed that nearly 500 families had had a police investigation for allegations of smacking or minor acts of physical discipline since the law was enacted, yet only 7 per cent had been serious enough to warrant charges being laid.
He highlighted a police report mostly covering the first half of last year which said officers had attended 456 child assault events, including 18 involving "smacking" and 58 of "minor acts of physical discipline".
The events in the latter two categories resulted in 10 prosecutions, one for smacking a child at least five times with an open hand on the buttocks, with no physical injury. The remaining nine prosecutions involved slaps to the head.
The outcomes were: suspended sentence, 3; nine months' supervision, 1; discharged without conviction, 2; withdrawn, 2; not guilty, 1; not sentenced by the time of the report, 1.
66 per centof parents would "smack to correct in future"
44 per centhad not smacked their children since the 2007 law change
49 per centthink law change "caused decline in discipline"
81 per cent would not report someone for smacking
63 per cent think law should be changed to allow hand smacks
75 per cent say 2007 law change has not changed New Zealand's level of child abuse
Source: Curia Market Research poll of 500 parents