This story was originally published in Newsroom.co.nz and is republished with permission.

The Government has been unapologetic for the record high prison population, but that confidence may be beginning to waver. Shane Cowlishaw reports.

Corrections Minister Louise Upston has sought advice about how to curb the surging prison muster, but what those options are remains a secret.

DAVID WHITE/ FAIRFAX NZ Labour's corrections spokesman Kelvin Davis says National is scared people will say it's soft on crime.

It comes as New Zealand's prison population is forecast to keep rising, with the possibility a new prison facility may not be big enough to cope.

In February, the Department of Corrections responded to a request from Upston for an "initial set of options" that could reduce the population.

Newsroom requested a copy of the briefing under the Official Information Act but it was heavily redacted, including all details about the ideas presented to the minister, on the grounds of protecting the "confidentiality of advice" of officials.

FAIRFAX AUSTRALIA The country's prison population, at 10,200, is the highest it's ever been.

Several other documents on the prison population have also been withheld in full.

New Zealand's prison populations sits at about 10,200 - the highest it has ever been.

Last year it was announced $1 billion would be spent building another 1800 prison beds, most of that going towards a new 1500-bed facility at Waikeria Prison in Waikato to open in 2020.

Now Corrections has confirmed that it has briefed the minister on the possibility of boosting Waikeria's capacity by another 500 beds to 2000. No detailed costings or plans have been provided to the Government and the matter has not gone before Cabinet.

Kelvin Davis, Labour's Corrections spokesperson, praised Upston for wanting to address the issue but was shocked the suggestions of how to do so had been withheld.

"Why they would redact suggestions beggars belief because surely we have to have a discussion around the various options and just because Corrections gives advice doesn't mean to say it's Government policy.

"What they're suggesting is not of national security significance, what they're scared of is people saying they're going soft on crime."

While much information is withheld, the briefing does contain some insight into how the prison population has risen so high – a surge of 20 per cent since 2014 – and the tough decisions looming.

"Long term, the Government will have a choice between the extent of additional investment in prison capacity, or policy and investment decisions across the justice sector that 'pull back' the demand curve," the briefing says.

"To be effective given the size of forecast increases, these decisions would likely need to involve changes to existing settings."

The rapid rise in prisoner numbers took the justice sector by surprise, with the briefing noting it was unexpected and had led to "substantial pressure" on prisoner accommodation and services.

The document reveals that some of the redacted options for reducing the population had been presented to Upston's predecessors in 2015 and 2016, but whether they were acted upon is unknown.

Upston herself refused to reveal what options had been provided to her, stating a range of ways to reduce pressure on the justice sector pipeline were being considered with a report due in November.

BAIL ACT BLOWOUT

At the National Party conference last month, Upston appeared onstage with her justice sector counterparts Paula Bennett and Amy Adams.

The trio thrilled the crowd, with Upston and Bennett putting the record prison muster down to fantastic work from the police.

"Criticism of police is not justified because we have more people in jail than ever before," Bennett said.

But the Corrections briefing squarely points the finger at law changes that have seen the remand population balloon.

In 2013 the Government changed the Bail Act to make it tougher to get bail, particularly for violent and drug-related crimes.

The briefing reveals that in reality, the changes led to a need for 10 times the number of prison beds initially estimated.

When the policy was designed, justice officials believed a mere 50 extra beds would be needed each year, but actual demand was for an additional 500.

Restorative justice changes had also created demand 10 times the original estimate of 10 beds a year.

It would be "useful" to understand why these figures had been so wrong, the briefing says.

Immediate, targeted funding focused on remand offenders was recommended to reduce the pressure.

Legislative amendments to victims' rights and sentencing laws plus a tougher stance on family violence has also likely played a part.

In 2011 the Government also passed the Criminal Procedures Act in an attempt to streamline the court system.

But the briefing described the changes as a failure, with no improvement in court disposal times.

Upston was unavailable for an interview, but in a written statement said the record prison population had been foreseen by her predecessor Simon Power in 2010.

While it was high, it was only a 23 per cent rise since 2009 compared to a 40 per cent increase that had occurred under the previous Labour Government.

She said the best way to reduce the prison population was to prevent people from entering the system and the Government's social investment approach was designed to do this, through reducing risk factors such as alcohol and drug addiction, family violence, and mental illness.

"We know that the earlier we intervene, the greater the likelihood will be of preventing offending and victimisation."

Davis described the Bail Act changes as short-sighted as the more people you locked up, the more people there were that would eventually come out worse off.

He accepted that previous governments had also neglected to address the issue of a rising prison rate, however.

"That's a fair comment, Corrections is an area that governments have been too afraid to touch because they'll be seen soft on crime, but the reality is we need to be smart on crime."

Tracey McIntosh, professor of indigenous studies at Auckland University, said the rising prison rate meant the disproportionality in terms of Maori incarceration rates were intensified.

It was critical to look at policies to prevent people being sent to prison rather than those aimed at locking them up, such as addressing the drivers of crime and social harm, she said.

"We have a tolerance, indeed some could argue an enthusiasm, for a high incarceration rate."

DEPORTING PRISONERS EARLY

One option that has been considered by the Government is deporting non-New Zealand citizens before the end of their sentence.

In a separate briefing obtained by Newsroom, Corrections provided Upston with advice on the current policy after she requested details.

The minister of immigration holds the power to release offenders to be deported early, but they must be serving a sentence of less than two years or have served a substantial portion of their sentence.

Michael Woodhouse, current immigration minister, has only granted one early release since 2013 while the number of prisoners liable for deportation is just 227.

Corrections raised several problems with adopting earlier deportations, including that it was unlikely the offender would be subject to any oversight when returned to their country.

"Changes to deportation policy may therefore have diplomatic implications for New Zealand," Corrections said in the advice for the minister.

"New Zealand does not enter into prisoner exchange agreements with other countries in order to allow prisoners to serve out their sentence in their country of origin."

The idea has shades of Australia's controversial law change in 2015 that has seen scores of New Zealanders sent back to their birth country.

The development caused outrage, with offenders who had lived for most of their life in Australia separated from their families and many offending soon after arriving back in New Zealand with no support systems.

Upston declined to answer questions on the subject, stating it was an immigration matter.