A police officer was justified in firing 21 shots at a driver who repeatedly tried to run him over, the Independent Police Conduct Authority (IPCA) says.
Police were told a firearm and a vehicle had been stolen in two separate incidents in the Coromandel area, on 28 August 2017.
An officer armed himself with a pistol and later found a man driving a Subaru and a woman driving a Holden.
After pulling one vehicle over, the man driving the second car drove towards the officer and rammed the patrol car's open door.
He then reversed in the direction of the officer and repeatedly tried to run him over.
The IPCA said the officer fired the shots in self-defence after believing he was in a vulnerable position and that he had no realistic way of hiding or escaping.
The officer fired multiple shots, intending to incapacitate the driver. No one was injured during the incident.
The man and woman were subsequently arrested and charged. Both pleaded guilty to unlawfully taking a motor vehicle and burglary, and the man also pleaded guilty to aggravated assault.
The Authority found that the officer was justified in arming himself, and in firing the shots in self-defence.
"The man could not be stopped by any other means than the use of a firearm", Authority chair Judge Colin Doherty said.
"The officer believed he was in a vulnerable position and had no realistic way of hiding or escaping.
"The other defensive options available (such as baton, pepper spray, or Taser) would have been ineffective against an attacker using a car as a weapon."
The Authority found that the officer breached police policy by not putting on ballistic body armour when he armed himself.
Police said the officer was extremely courageous.
In a statement, Waikato district commander Superintendent Bruce Bird said it was a fast and evolving situation in which the officer made judgement calls that were supported by the IPCA.
"This was a very traumatic experience for the staff concerned and their colleagues, particularly in Eastern Waikato, who we continue to support."