Taser guns will be available to about 170 frontline police officers this Friday, despite the fact that the decision was not subject to public submissions.
Under a 12-month trial, officers in Auckland and Wellington will have the guns to use when physical violence is threatened.
The staff allowed to use the Taser have had one day of training. Each was subjected to a Taser stun, which causes the muscles to contract uncontrollably.
Superintendent John Rivers yesterday defended the police decision to go through with the trial without inviting public submissions.
"The justification [for the trial] was sufficient to enable the police executive to sign off the proposal. Public submissions were not identified to be an essential part of the process."
He added that public debate was essential and police were open to talk to interested groups.
"There has been significant correspondence with groups, but at the end of the day the police decision was an operational decision.
"The fact is that there's sufficient matters going on in and sufficient justification for policing violence and disorder, and there is a need to trial it."
But opponents say the decision to use the Taser was fast-tracked and brings an unknown and dangerous weapon into New Zealand society.
"Police are rushing this through and there has been no formal consultation process," said Marie Dyhrberg, spokeswoman for the group Campaign Against the Taser.
"There is no real rush right now to do this, and we don't know enough about the Taser. The US Justice Department is reviewing Tasers right now. Why don't we see what they have to say."
While there were situations where the Taser should be used, she said, the police guidelines for proper use were too fluffy and problematic.
"The guidelines aren't clear enough and don't define enough.
"I expect the trial period to be squeaky clean, and when the spotlight is off and many more are issued with Tasers, with loose controls in place, that's when the real danger is going to occur."
The guidelines state that Tasers may be used only to defend people, make an arrest or resolve an incident where there is a threat of physical injury and less force cannot be used.
Mr Rivers said the threshold for Taser use was "very high" and would not be abused. Police guidelines state that Tasers should not be used against non-aggressive people.
"Over and above the public benefit outweighing the medical risks, the key thing is that the Taser provides an option before the potential recourse to lethal weapons."
Mr Rivers did not want to speculate on how widely the Taser might be deployed around the country if the trial were successful.
Police said each person Tasered would have a medical examination.
RULES OF ENGAGEMENT
Police may use Tasers only to:
Defend themselves, or others, if they fear physical injury to themselves, or others, and they cannot reasonably protect themselves, or others, less forcefully.
Arrest an offender if they believe on reasonable grounds he or she poses a threat of physical injury and the arrest cannot be effected less forcefully.
Resolve an incident where a person is acting in a manner likely to physically injure themselves and the incident cannot be resolved less forcefully.
Prevent the escape of an offender if they believe on reasonable grounds that he or she poses a threat of physical injury to any person, and the escape cannot be prevented less forcefully.
Deter attacking animals.