A failure to address high Maori reoffending rates means the Crown has breached its Treaty of Waitangi obligations, the Waitangi Tribunal has found.
In a report released today, the tribunal said the gap between Maori and non-Maori reoffending rates was "longstanding and substantial", and contribute to the high number of Maori behind bars.
Maori make-up half of New Zealanders in prison, despite accounting for 15 per cent of the national population.
The inquiry followed a claim by retired Napier probation officer Tom Hemopo, who last year filed a claim targeting the Department of Corrections and alleging no high level commitment had been made to reduce the number of Maori in prison.
The tribunal examined efforts by Corrections to cut the rate of reoffending by 25 per cent, and said the most recent statistics showed Maori progress towards this target had dramatically slowed.
The gap between Maori and non-Maori progress towards the target has widened.
The tribunal found there was a broad justice sector target to reduce Maori reoffending but Corrections had no specific plan or strategy to do so, and no specific budget for that work.
Despite its failings the Crown has not breached its partnership obligations, the tribunal found, given Corrections good faith attempts to engage with iwi and hapu.
Recommendations from the tribunal's report included a new Maori-specific strategic framework be established by Corrections, and a Maori-specific target be set around reoffending, with regular public reporting on progress.
A dedicated budget was also needed to resource this work, the tribunal recommended.
Those recommendations largely covered what was sought by Hemopo, who retired in 2011 after 25 years working as a probation officer.
Aaron Perkins QC, appearing on behalf of Corrections in July's hearings, pointed out a number of Maori-focused initiatives had started since his retirement in 2011.
That included the creation of a director of Maori position, who heads a dedicated team of 24 staff, and is tasked with the development of a strategy to reduce Maori re-offending.
Corrections had "dozens and dozens" of regional-level initiatives partnering with Maori at a local level, Perkins said, and agreements in place including with Te Taumutu Runanga.
Prime Minister Bill English said more needed to be done, not just for Maori but all offenders. It was not acceptable that half of prisoners were Maori.
"The prison population itself is too high. That is why we are doing things like changing the way the Government cares for children in state care, because there is a fairly predictable track for some of them to prison 15, 20 years in the future."
English said in the past four years there had been "a big lift" in mental health, literacy, and drug and alcohol programmes for prisoners.
"We believe we have lifted the effort for all prisoners in the interests of the safety of the community."
Corrections Minister Louise Upston said the report highlighted some areas Corrections was already working on, including an accord with Kingitanga.
"It is a problem and a challenge for Government, but it has been a long-standing and complex issue for us to solve."
Maori Party co-leader Marama Fox said she was glad the report had been released, and there were serious problems with the justice system's "institutionalised racism".
"I think there are a number of recommendations that we can take seriously and bring in front of the Government," Fox said, adding she had scheduled a meeting with Upston.