A police officer who suffered a dislocated jaw and concussion after a teenager coward punched him in central Wellington may suffer effects for the rest of his life, a court has heard.

His attacker, 19-year-old Matua Ratana, appeared in the Wellington District Court today asking for a sentence to come up if called upon, but any potential chances of that vanished as the judge was told of Ratana’s previous entanglement with the law.

Judge Arthur Tompkins had earlier declined to discharge Ratana without conviction for the “serious and unprovoked assault”, saying he was “lucky he’s not facing a manslaughter charge”.

Ratana had pleaded guilty to injuring with reckless disregard, and resisting arrest.

About 4am on Sunday, November 6, Ratana was drinking on Courtenay Place in Wellington’s central city with a group of close female friends whom his lawyer said he considered sisters.

Police officers patrolling the area noticed two women fighting, and began moving through the crowd to break up the fight, Judge Tompkins said. The fight is not believed to be connected to Ratana’s female friends but, in the process, a police officer trying to make his way to the fight pushed one of them.

The constable had a dislocated jaw and a concussion after the attack.

Ratana’s lawyer, Ainslie Teki, said at an earlier hearing he “saw one of his friends being pushed around by a police officer and he reacted in a way that he thought was protecting her and he did swing his fist at the police officer”.

Judge Tompkins said Ratana hit the officer with a closed fist on the side of his head, knocking him out and causing him to immediately start bleeding from the mouth. The officer was hospitalised and suffered a concussion.

The officer was “painfully aware” if the punch had been just a little bit higher “the result could have been drastically different”, Judge Tompkins said at the earlier hearing.

Ratana then fled the scene on foot and struggled against arresting officers, who had to pepper spray him. One of the officers suffered a rotator cuff injury to their shoulder during the arrest.

Teki earlier said Ratana’s actions in punching the officer were “in the heat of the moment” and influenced by a “mistrust” of police. She said he had a bad experience with police once where he was attacked by a police dog despite not doing anything wrong.

He wanted to engage in Restorative Justice but that did not happen. He has also made a donation of $100 to a child cancer charity.

Ratana was 18 at the time of the coward punch offending and had no previous convictions - but the police prosecutor in court today pointed out this did not mean Ratana had not been before the court. She referred to previous charges for assault, wilful damage and disorderly behaviour with intent to incite violence.

One incident in Whanganui last year happened when police received reports Ratana and his friends were smashing glass bottles on the footpath.

Ratana became “aggressive and abusive towards police” and had to be taken to the ground and subdued with a police dog, the prosecutor said.

He was later searched and found to have a 20cm kitchen knife in his possession. Ratana received a diversion for that offence.

Teki had asked for a sentence to come up if called upon - meaning, aside from a conviction, Ratana would not suffer a penalty unless he committed further offending within a certain timeframe.

She said he was not raised to use violence, but was “quite protective of wāhine” and was “looking out for the safety of his vulnerable female friends after seeing a fight break out”.

But the prosecutor rejected that proposal as “highly inappropriate for a charge of this kind”, saying it “doesn’t take into account the impact this is going to cause for the victim potentially for the rest of his life”.

Judge Tompkins said the victim suffered a dislocated jaw and continued to suffer psychological harm from the incident.

He declined the sentence to come up if called upon, instead adopting a sentence of nine months’ supervision. Ratana may also have to attend counselling and treatment for alcohol abuse and violence.