Labour is going into the next election with a justice reform platform aimed at boosting confidence that innocent people are not being sent to prison.
The party is developing a policy which would see new rules affecting everyone from the police officer to the Governor-General.
It comes as a new book into the murders of Harvey and Jeannette Crewe - The Case of the Missing Bloodstain - also calls for justice reforms.
Farmer Arthur Allan Thomas was twice convicted and then pardoned of murdering the couple in a case which featured claims of police planting evidence.
Author Keith Hunter said the Crewe murder case destroyed the public's trust in the justice system. He said subsequent cases around which there were questions, including the murder convictions of David Tamihere and Mark Lundy, had further eroded the public trust.