A constable who Tasered a mentally ill man twice to stop him running away was in breach of police policy and his actions were a "disproportionate and unjustified" use of force.
But as a result of the incident in April last year the Independent Police Conduct Authority (IPCA) has recommended police review the policy to allow officers to Taser people trying to evade arrest.
The then 37-year-old Hokitika man complained to the IPCA that it was unfair to Taser him a second time when he was "spread-eagled" on the ground.
He also complained a second constable kicked him in the head and used their shoe to pin him down by the neck, that he never received medical attention for the Taser injury despite asking for it, and that he was brushed off when he tried to make a complaint that night.
However during its investigation the IPCA found the first constable should not have Tasered the man as he was fleeing because the police Taser policy states the weapon can only be used on an actively hostile person.
It said discharging the Taser only two seconds later for another five seconds while the man was lying face down on the ground with his hands pinned beneath him was unjustified.
In its ruling released today the authority said the man, known as Mr X, had threatened five people over the course of several hours on the evening of April 21, 2015.
Officer A caught up with the offender about 11pm that night and chased him toward a residential property.
He yelled "Stop or I'll Taser you". Mr X tripped and as he got up to continue running away Officer A Tasered him in the lower back.
The constable said he used the Taser a second time because he knew Mr X had a history of mental illness, he was concerned the man may have a hidden weapon, he was without back-up, because the man was of large stature, and because he had threatened five people earlier in the night.
But Taser camera footage showed the constable commanding the man to put his hands behind his back once he was on the ground, but as Mr X tried to comply he was Tasered a second time.
"The footage does not show Mr X being aggressive or assaultive towards officer A."
The footage cleared Officer B of any wrongdoing, showing that he did not kick the man in the head or kneel on his back.
Back at the station police said the man was "raging" so they kept him in handcuffs and decided against calling out a doctor, part of the police policy for appropriate Taser aftercare.
The authority said the man should have been seen by a doctor after he was transported to Greymouth Police Station when he had calmed down.
The police watchdog also said two supervising officers were wrong to accept the constable's use of the Taser was not in breach of police policy and was justified, in a follow-up report.
It said it could not make a finding on whether the complainant was brushed off when he tried to make an initial complaint that night because of conflicting evidence.