He followed the car as it exited the motorway, drove through a red light, and then stopped at a residential address on Bentley Rd.
The off-duty officer parked his car near the address to observe the occupants of the stolen car, updating NorthComms until police could arrive to assist.
Tai briefly spoke to the off-duty officer, who remained in his car, before the teenager returned to the stolen car and drove away with two passengers.
A marked patrol car arrived as Tai pulled out on to Bairds Rd and was able to follow.
The pursuit started with police matching the speed of the fleeing car of 90-100km/h in a 50km/h zone.
After the stolen car barrelled through a red light police began to slow down, losing sight of the vehicle.
It was then decided to abandon the pursuit.
As they rounded a corner on Bairds Rd police came across the smashed car.
The authority chairman, Judge Colin Doherty, said it had been appropriate for the off-duty officer to intervene in this incident and to follow Tai until on-duty police could assist.
"The authority is also satisfied that the police officers who engaged in the pursuit with Mr Tai complied with the law and police policy."
The authority also found that police provided appropriate emergency medical assistance until ambulance services arrived at the scene of the crash.
In July 2017, the IPCA and the New Zealand Police commenced a joint review of police pursuits.
The aim of the review was to better understand the pursuit environment, and to identify any current issues with police management of these events.
The review will also identify areas of good practice.
It is intended that a report will be made publicly available later this year.
Police superintendent Jill Rogers said she supported the actions her staff had taken.
Welfare referrals were provided to staff and support was also provided to Tai's family, she said.
"Every death on our roads is a tragedy, and this is the absolute last outcome that any of my staff wanted," she said.
"This fatal crash could have been avoided had the driver chosen to stop for police, and this incident demonstrates the serious risk involved when drivers choose to flee the scene.
"We ask that people stop if requested by police and to not put their own life, or the lives of innocent members of the public, at risk by attempting to flee from police."
