The Independent Police Conduct Authority (IPCA) has cleared officers of wrongdoing in two separate pursuits which left three teenagers dead earlier this year.
In the first pursuit, in the early hours of Sunday 24 January, a 15-year-old girl was driving a stolen car at 115km/h in a 50km zone in Papatoetoe, Auckland.
The pursuit lasted four minutes, and the driver went through two red lights, before crashing into another vehicle.
Her 16-year-old passenger, Eden Nathan, died as a result of the collision.
The driver, who was left with extremely serious injuries, remains in residential care according to the IPCA.
The second pursuit, in Masterton, unfolded in the early hours of Sunday 31 January.
Police said they saw a stolen Honda with four teenagers inside speed up and drive through a stop sign at over 100km/h, heading towards the centre of the town.
Officers gave chase but decided the pursuit was too dangerous to continue after 30 seconds and abandoned it.
Police said they saw the car speed over five raised courtesy crossings, then turn left sharply and crash.
Two 15-year-old passengers, Pacer Willacy-Scott and Hoani Korewha, died in the crash.
The 14-year-old driver and other passenger were left with minor injuries.
The IPCA found that the officers involved were "justified in commencing both pursuits and conducted thorough risk assessments throughout".
The IPCA chair, Judge Sir David Carruthers, has laid the blame with the drivers.
"Both of these crashes were caused by the actions of the teenage drivers. They resulted in the tragic and needless loss of life or serious injury to several young people," he said.
National Road Policing manager Superintendent Steve Greally said the pursuits were "tragic".
"There is no infringement notice or conviction that is worth the loss of lives we've seen in these two incidents."
"Both of these tragic outcomes could have been avoided had each driver stopped when requested to by police,"