A policeman has broken ranks to sound warnings about arming the force.
The Police Association has repeatedly called for all frontline officers to bear arms routinely.
At present, guns can be accessed from stations and patrol cars when a threat is identified.
But new research to be presented at an Australasian criminology conference this week says officers and the mentally ill will be much more at risk if police are armed.
Ross Hendy, a Kapiti policeman, explored the strategic impact of routinely arming the police as part of his Victoria University masters degree in strategic studies.
"The Police Association is for general arming because of the increasing number of assaults on police and they believe it will protect the officers' safety, but there are real risks around that. In my view it's not necessarily going to help."
Hendy visited Norway, Sweden and Britain to speak to police and academics about the effect of officers carrying guns.
Staff in England, Wales and Norway are not routinely armed but the Swedes are.
"In Sweden, the risk is ... when they go into dangerous situations, they think, 'I can deal with this because I have a firearm.'
"In Norway, they wait for more staff ... In Sweden, they don't wait, and find themselves in dangerous situations."
Hendy will present his paper at a conference to be co-hosted by Victoria University and the Australian and New Zealand Society of Criminology on Tuesday.
He said the routine arming of Australian police had led to a marked increase in mentally ill offenders being fatally shot. "That's a real risk to public safety."
The Office of Police Integrity in Victoria found 53 per cent of fatal police shootings from 1990 to 2004 involved individuals suffering from a mental illness or disorder.
Hendy said more training was needed for officers dealing with the mentally ill.
Police Association president Greg O'Connor said he, too, had just come back from Norway.
"Since the Utoya Island shooting (in which Anders Breivik killed 69 people in July 2011), the police association in Denmark has called for general arming," he said.
Police needed to be armed to protect themselves and the public.
"If you are being hunted by a mobile offender on the rampage you don't want police to wait. In an 18-month period back in 2009, nine police officers were shot in the course of routine policing. Had they been armed, they would have been able to protect themselves."
Before yesterday's shooting in New Plymouth, the most recent case that sparked renewed calls for police to be armed was when Kawhia constable Perry Griffin tried to arrest a 19-year-old in January.
Though he was carrying a pistol, he was allegedly attacked, stripped of his weapon and needed help from firefighters.
Jackie Maikuku is facing charges of aggravated assault and assault with intent to injure. His father, Jackie snr, who was initially also charged, has laid an assault complaint against Griffin.
Maikuku snr told the Herald on Sunday police were still investigating his complaint against Griffin, and the Independent Police Conduct Authority was also investigating. "(Griffin) provoked the situation, I believe," he said.
He said police should not be routinely armed as it was better for officers to take a step back before deciding to pull a gun on offenders.