The Taser gun - which fires up to 50,000 volts into its victim - is a potentially lethal and unnecessary weapon that police officers could use and abuse as a compliance tool, a group of opponents say.
"There is no possible justification for the Taser's introduction," says barrister Marie Dyhrberg, spokeswoman for the Campaign Against The Taser.
Police are beginning a 12-month Taser trial in September in Auckland and Wellington. If approved, the Taser could become standard issue for frontline staff in selected districts.
About 100 people attended a meeting arranged by the campaign in Auckland last night to raise concerns. It was chaired by former Governor-General Sir Paul Reeves.
Ms Dyhrberg said there were already examples of police misusing power, citing the case of Scott MacDonald, who was pepper-sprayed by police while handcuffed and lying on the ground after last month's Fight for Life.
"Pepper spray is now being misused in ways never anticipated by New Zealanders when it was introduced."
Several people who claimed to be victims of police mistreatment had similar concerns that the Taser would become a tool for officers to get what they wanted, regardless of whether violence was a threat.
Matthew Donaldson said he was near Karangahape Rd last year when police, suspecting him of having drugs, threw him against a wall and to the ground.
"[Police] would rather get compliance through violence."
Campaigner Rodney Harrison, a Queen's Counsel, said the group would mount a legal challenge, if necessary, to "overturn this obscene decision".
The case would look at human rights issues and how the Taser introduction was approved.
Dr Harrison said using the Taser - which has played a role in the deaths of more than 150 people in America in the past five years - amounted to cruel torture.
He called for an independent inquiry into the effects of arming police with Tasers and condemned the force for telling half-truths about the risks and dangers of the weapons.
Police national headquarters spokesman Michael Player said officers were happy to talk to groups with concerns.
But he said police would not be open to receiving public submissions and, barring any incompetent misuse during the trial, the guns would likely be approved.
Mr Player said frontline police officers needed to have a less-lethal option than a firearm when threatened with violence.
What is a Taser gun?
The air Taser stun gun looks like a pistol but uses compressed air to fire two darts that trail electric cables back to the handset. A laser sight allows the shooter to aim accurately.
When the darts strike, a five-second charge is released down the cable. Electrical signals - taser waves - overpower the body's normal electrical signals, confusing the nervous system. The suspect's muscles contract uncontrollably, causing temporary paralysis.
How effective are they?
Very. People are incapacitated for about five seconds and then usually need some recovery time to return to normal.
As part of a British trial, Greater Manchester Chief Constable Michael Todd was shot with one and reportedly screamed in agony.
"I couldn't move, it hurt like hell," he said afterwards. "I wouldn't want to do that again."
Are they safe?
That's the crux of the issue. Rick Smith, chief executive of Taser International, the company that makes the guns, is on record as saying they are "not risk-free" but they are among the "safest use-of-force" options for the police.
In July 2004, a subcommittee of Britain's Defence Scientific Advisory Council looked at the medical implications of Taser use and concluded: "The risk of life-threatening or serious injuries from the M26 laser is very low."
But Amnesty says the high-voltage guns have been linked to more than 70 deaths in America. Others put the death toll at 150.
It has warned they cause "intolerable pain and may exacerbate the risk of heart failure" in people under the influence of drugs or with health problems.
Why do police here want to use them?
They have watched other countries that have introduced Tasers and say they are an "effective, less lethal intervention".
They would particularly be used against unarmed or lightly armed but highly aggressive people and people under the influence of mind-altering substances, solvents or alcohol.
Police say Tasers have been successful overseas in dealing with violent offenders and have significantly reduced the number of injuries to offenders and police.
This has resulted in fewer complaints against the police.
What's the opposition?
Community groups and several high-profile individuals, including former Governor-General Sir Paul Reeves, have formed the Campaign Against the Taser.
They say the gun penetrates the skin, delivering a 50,000-volt electric shock, which "has been responsible for causing or resulting in deaths in other countries".
They believe there has been no independent, impartial and thorough inquiry by scientific, legal and law enforcement specialists on the use and effects of Tasers in New Zealand.
They are also worried by the absence of strict rules, safeguards and monitoring procedures to prevent the misuse of the Taser.
What's the New Zealand plan?
Taser guns are due to be tested in the North Shore/Waitakere/Rodney, Auckland City, Counties Manukau and Wellington districts this month. Police say they will follow the British path, which saw Tasers introduced after they were tested in five constabularies.
Policy was comprehensively developed including medical protocols for the after-care of offenders subjected to Taser action and the guns were issued only to specially trained officers.
The New Zealand trial will use the X26 model with five watts of voltage compared with the older M26 26-watt model used mainly in the US.
Where else are Tasers used?
In the United States, Canada, Britain and parts of Australia.