Lobby group Rethinking Crime and Punishment says a joint police and iwi strategy is likely to be more effective in cutting the Maori incarceration rate than any specialist programme run by prisons.
Police and some tribal representatives launched Turning of the Tide in December which aims to cut the prosecution of Maori people by 25% within six years.
Rethinking Crime and Punishment director Kim Workman praises the strategy.
He believes Turning of the Tide will do far more good in reducing the number of Maori in prison than programmes such as Maori Focus Units.
Mr Workman says once people are put in front of a judge the chances are that re-offending by Maori increases.
He believes the police strategy will do far more than what can be done in prison because it diverts Maori offenders away from the justice system.
Instead, he says they can receive help from whanau and community services.
Official figures show that of 400 inmates released from the five Maori focus units in the 2010-2011 year, 108 went back to prison within 12 months. The reoffending rate is slightly lower than for inmates in other parts of the prisons.
Mr Workman says Maori Focus Units appear to show promise but have a long way to go.