"He decided to arm himself with a pistol because he thought the [man's car] may have been linked to an armed robbery that had occurred in Hamilton six hours earlier," the report said.
The officer laid down spikes in an attempt to stop the man's vehicle. Instead, the man tried to make a U-turn in a bid to avoid the spikes; which would have seen him travelling down the wrong way on State Highway 1.
"During this time, the officer ran towards the rear of the [car]. As the man began reversing to complete the U-turn, the officer fired three warning shots into the ground in an attempt to make him stop.
"The authority found that neither the officer's decision to arm nor to fire warning shots were reasonable."
Authority chairman Judge Colin Doherty said there was no sound basis for the officer's decision to arm himself in the first place.
"He then unnecessarily placed himself in a dangerous situation," Judge Doherty said.
"Rather than firing the pistol that he should have been carrying, he could have jumped out of the way of the reversing car."
Waikato District Commander acting superintendent Warwick Mōrehu said authorities accepted the IPCA report and its findings.
He said police acknowledged that the armed officer had made errors of judgment in carrying out the arrest.
"Police deal with fast-moving and ever-changing situations every day and split-second decisions need to keep the community and police safe.
"In this instance, we acknowledge that some of the decisions made by officers could have been better and alternative tactical options should have been considered.
"However, we note that no one was injured and this high-speed fleeing driver incident was resolved successfully.''
Mōrehu said the officers involved had since been supported and had undergone intensive training to help deal with situational awareness, decision making and use of tactical options.
The man involved in the incident was stopped when other police officers arrived and used their own vehicle to push the man's car off the road.
He surrendered, but as officers tried to pull him from the car onto the ground, he held on to a seatbelt.
Another police officer then kicked him in the midriff in order to get him to let go of the seatbelt.
The authority also found that officer's actions to be unjustified.