The lobby group, Rethinking Crime and Punishment, says an independent centre should be set up to look at why the rate of Maori imprisonment is so high.
Forty percent of Maori men over the age of 15 have been in prison or served a community-based sentence, and Maori are imprisoned at six times the rate of non-Maori.
The group's director, Kim Workman, says he is concerned about the situation in poor areas where there is a high Maori population.
He says research is needed into what he calls the disproportionate treatment of Maori within the criminal justice system.
Mr Workman says governments have avoided addressing the issue because doing so would be an admission that there's an element of racism in New Zealand.