A top judge says a long-term decline in the rate of school expulsions for bad behaviour is paying off in a falling crime rate.
Sir David Carruthers, a former Chief District Court Judge who now heads the Independent Police Conduct Authority, says the crime rate has dropped by 15 per cent in the past three years and growth in prison rolls has stalled.
"There were forecast to be 9200 to 9300 prisoners today. In fact we are holding at about 8600," he said.
He said crime rates were also falling in other Western nations for various reasons, including declining cocaine use, more electronic surveillance and demographic changes - youths aged 18 to 24, who commit most crime, are a declining proportion of ageing populations.
But he told a criminology conference in Auckland yesterday that another factor in New Zealand was a drive to reduce school suspensions and expulsions and a growing use of "restorative" procedures aimed at helping offenders apologise to their victims and restore good relationships.
"In an under-the-radar way over the last few years, restorative practices in education have begun to play a really important part in preventing exclusions and stand-downs from schools," he said. "It's very clear that this may have a part to play in the continuing reduction of crime."
Principal Youth Court Judge Andrew Becroft said in July that 70 per cent of the most serious youth offenders were not in school, and if there was a "magic bullet" to reduce youth crime it would be to keep them in education.
Education Ministry figures show that school suspension rates have been declining for at least 12 years, from 7.9 for every 1000 students in 2000 to 5.2 last year.
The decline has been most dramatic for Maori students - down from almost 20 to under 12 for every 1000 Maori students.
Full exclusions of students under age 16 have also trended downwards over the same period, from 2.7 to 2.1 for every 1000 students, and so have expulsions of students aged 16 and over, from 2.5 to 1.6 for every 1000 students. Excluded students have to be accepted by another school but expelled students may be kicked out of schools forever.
Former Prison Service head Kim Workman, who now runs think-tank Rethinking Crime and Punishment, said crime rates had trended downwards even longer. The crime rate peaked in 1991 at almost 13,000 offences for every 100,000 people, and fell to about 9000 crimes for every 100,000 people this year.
The murder rate leapt from about 2.5 murders for every million people in 1950 to just over 20 per million around 1990, and has halved to between eight and 10 per million in the past two years - the lowest since the mid-1980s.
Mr Workman said this was partly because society was ageing and partly because women no longer felt trapped in violent relationships.
"If it's not working, they tend to walk away," he said.
He said a change in police strategy had also reduced the overall crime rate in the past two years, with more neighbourhood policing targeting high-crime areas, more use of diversion, and new police safety orders for less serious domestic situations, allowing police to order an offender out of the house for up to five days without recording an offence.