The police have apologised to a leading gang researcher, after they blocked him from getting basic data due to his links with gangs.
University of Canterbury sociologist Jarrod Gilbert wanted the information for research on alcohol and violence.
The police have now granted Dr Gilbert access to the data.
Police deputy chief executive Mark Evans said they were also changing the guidelines for how researchers were vetted, and were updating the contracts they asked researchers to sign when they did release information.
This would remove any language that might be interpreted as restricting the independence of academic research, Mr Evans said.