Prison reformers said reducing the number of New Zealanders in jail cells was a hugely important goal because incarceration was expensive, often did not work as a deterrent, and could be particularly harmful for young people.
The Government has not set an official target for reducing prisoners. But it has estimated that if it reaches its goal of a 25 per cent reduction in reoffending by 2017 that there will be 600 fewer prisoners.
Corrections Minister Anne Tolley said this reduction was still expected to be achieved. She emphasised that the prison population had been forecast to reach 10,000 by December 2013, but was now below 9000.
The department's expansion of drug and alcohol programmes and an intense focus on educating and training prisoners had partly contributed to a 12 per cent drop in reoffending since 2011.
But the minister admitted this had not yet translated to a big fall in the number of people being locked up.
"There will be lag effect before we see a reduction in prisoner numbers, because prisoners participating in [the programmes] will need to complete their sentences and then spend time in the community following their release without reoffending."
The lowest crime rate in 24 years had also not made a significant difference to the imprisonment rate.
Justice experts praised the strong focus by Corrections on alcohol abuse and education, but identified a number of reasons for why its strategies had not yet dented the total prison population.
Rethinking Crime and Punishment spokesman Kim Workman said treatment for alcohol abuse did not extend beyond prison.
"So you then end up with a judiciary feeling that if they want somebody to receive treatment they have to send them to prison rather than looking at a community-based alternative," he said.
Mr Workman believed the low reoffending rates were in part due to "statistical juggling", such as giving some offenders warnings instead of locking them up.
"That's an administrative shift that will count as a drop in reoffending ... but nobody has said that their behaviour has changed."
He recommended that the Government set a concrete goal for reducing the prison population and change its policy to stop locking up non-violent offenders who faced sentences shorter than six months.
Prison numbers were expected to stabilise or fall regardless of state intervention because an ageing population meant fewer young people, who committed the most crime.
Mr Workman said that as a result, the Government should aim for a more ambitious target than 600 fewer prisoners.
