Police say they have heeded the recommendations of a wide-ranging investigation into the deaths of 27 people in police custody over a decade.
The Independent Police Conduct Authority report found eight out of ten of those who died in police custody during the ten-year period from 2000 to 2010 were under the influence of drugs or alcohol.
The most common cause of death was suicide by hanging, of which there were 10 cases. Almost half of those who died were Maori, and all but one were male.
IPCA Chairman, Judge Sir David Carruthers, said deaths in custody were uncommon.
"While it is rare in New Zealand for people to die while in police custody, such deaths can be controversial.
"When a person dies while he or she is in custody, it has a serious impact on both their family and the police officers involved."
Carruthers said that public confidence in the police may also be affected by deaths in custody.
"While not all deaths in custody are foreseeable or preventable, in some cases the actions or omissions of police staff may be a contributing factor," he said.
Assistant commissioner Nick Perry responded by saying that police had already embarked on many of the recommendations listed in the IPCA report.
Police had spent $3 million suicide-proofing cells, removing hanging locations. They had learnt the hard way that pillowcases and blankets could be ripped and used as nooses.
He said: "Every death in custody is a tragedy and we don't want any to occur. We are dealing with people here who have consumed alcohol and drugs, there is often a psychological issue. At least 50 per cent had serious health issues."
Perry said just two people had died in police custody in the past three years.
"There is always that risk there, but frankly, expecting our officers to carry out a health assessment in the midst of trying to subdue somebody is totally unrealistic."By Bevan Hurley @BevanHurleyHoS Email Bevan