An Auckland police officer who tasered a man in the back was not justified in using the weapon, the Independent Police Conduct Authority (IPCA) has ruled.

Photo: NZ Police

The man who was tasered suffered facial injuries and was knocked unconscious when he fell to the ground after the taser was used.

He was arrested after he was seen speeding on a motorcycle around the Auckland suburb of Henderson on 4 March last year.

After initially stopping for the police officer, the man ran away after backup was called and the taser was used following a brief chase.

The officer later told the IPCA he was worried the man might take the police car.

The IPCA found that the officer was justified in arresting the man for his dangerous driving and some outstanding warrants for his arrest, but he was not justified in pointing or firing his taser at the man.

For police to use a taser, the person involved must be "showing an intent to cause harm, expressed verbally or through body language or physical action", according to police policy.

Authority chair Judge Colin Doherty said the officer had other options available to him and the victim was not presenting an immediate threat.

"Although Officer A felt vulnerable, Mr X's behaviour was not assaultive, and Mr X was not presenting an immediate threat. Officer A had other options available to him," she said.

The Authority also found that the officer should have provided medical assistance immediately after the man was tasered, although appropriate steps were taken to ensure the man's safety after backup arrived.

Police said they accepted the report and acknowledged other options were available.

"Our officer made an assessment based on the information available to him at the scene and feared this offender was going to potentially put members of the public at risk, however we acknowledge that with hindsight, there were possibly other options available to the officer," Superintendent Tusha Penny said.

But Superintendent Penny passed the blame onto the offender for running in the first place.

"Ultimately, if this offender had listened to the police officer rather than attempting to run off and resist arrest, then this would have been resolved in a much simpler manner."

Police said lessons had been learnt and they would "continue to provide further tactical communications training" to staff.

The offender was charged with resisting police, driving dangerously, possessing methamphetamine and failing to comply as an unlicensed driver.

He was sentenced to two years intensive supervision, 200 hours community work and was disqualified from driving for six months.