Punishments dished out by judges could soon be influenced by cutting-edge computer data modelling on offenders' behaviour.
More than a million dollars will be spent on a system that will help indicate what could happen to criminals later in life depending on the severity of their punishment.
Judges have already been told that in certain cases a fine could be a better option than community work, after analysts found criminals getting the latter were more likely to reoffend and rely on the dole.
Justice Minister Amy Adams believes the work could radically change the way policymakers, judges and the general public think about the balance between rehabilitation and punishment.
"It's almost amazing that, to date, it has been done more on a societal instinct, really, as to what we think is right.
"For the first time now Government is starting to use information it has across sectors, across agencies in a much more analytical way. I think this will inform not just policy, but inform a good discussion amongst judges around the sorts of options they take."
High-level advice about the effect of long-term jailing on reoffending was already available, Ms Adams said, but the development of actuarial-type modelling would give much more detail.
Information such as an offender's age and criminal history could be matched with possible sentencing or rehabilitative options to see the likely outcomes.
"To almost know case-by-case ... the likely outcome of each of those interventions ... will be a huge step forward for policy-makers, funders, Governments, judges - everyone in the sector," Ms Adams said.
The funding commitment of up to $1.5 million from the Justice Sector Fund follows a flagship piece of work looking at what happened to offenders in comparison groups who were sentenced to community work or fined.
Offenders given community work were found to be 4 to 7 percentage points more likely to be reconvicted within two years, compared with offenders who were fined.
Offenders given community work are also more likely to be on the dole following conviction, compared with those who are fined, by about 5 percentage points.
If 1000 offenders were instead fined, officials put benefit savings at $1.5 million to $2.5 million over three years, with 40 to 80 fewer people reconvicted within two years.
The analysis - since shared with judges - used Statistics NZ's Integrated Data Infrastructure (IDI), which provides recently-linked data from the tax, benefit and justice systems, and anonymised information on all convicted offenders.
Treasury has also used the IDI and last week released research that highlighted indicators that increased the likelihood of children suffering hardship later in life.
Finance Minister Bill English is championing that work.
Labour's justice spokeswoman, Jacinda Ardern, said she supported evidence-based policy and sentencing, but extreme care would be needed.
Investing in justice
Justice Minister Amy Adams has green-lit the development of modelling that will indicate the likely outcomes of sentencing options, including reoffending, employment and benefit use.