A teenage love affair led to a police inspector's emotions running high and resulted in "an abuse of power and authority" with an alleged kidnapping, a jury has heard.

Inspector Hurimoana Dennis, 52, and Sergeant Vaughan Perry, 45, have been on trial in the High Court at Auckland for the past two weeks before a jury and Justice Edwin Wylie.

They were jointly charged with twice kidnapping a then 17-year-old boy in 2015.

The young Auckland man, now 19, alleges the inspector and sergeant locked him in a prison cell, threatened him with a rape charge, and "deported" him to Australia to end his relationship with a 15-year-old girl.

Crown prosecutor Brian Dickey today asked the jury to consider the social reality of teenage behaviour.

"These two young persons are going to have a sexual relationship with each other. History tells us this, life experience tells us this," he said.

"This is not a 56-year-old man who's groomed a 12-year-old-girl, 14-year-old girl, into consensual sexual intercourse.

"These are both teenagers - sure it's foolish, sure it's risky, sure they shouldn't be doing it, [but] they are not the first teenagers to fall in love and act recklessly," he said.

The teens' families had been arguing over the relationship and before the alleged kidnapping the boy's mother filed a formal complaint with police about her son.

However, Detective Sergeant Neil Hilton, the officer tasked with the complaint, determined that no charges should be laid.

Dickey said there was no public interest in charging the teen with statutory rape.

The prosecutor asked the jury: "Isn't it better that the two remain under [the girl's mum's] roof, rather than run off?"

The teen boy was living at his girlfriend's home as the two families feuded, and Dickey added there was no debate about if the boy was allowed to live there.

"He was 17-year-old and he was entitled to live where he chose. And no one will be able to tell you any other way because that is the law."

Sergeant Vaughan Perry and Inspector Hurimoana Dennis at the start of their High Court trial. Photo / Greg Bowker

However, Dennis' counsel Stephen Bonnar QC said the teen was committing a crime and wasn't just in breach of 1950s ideals.

"He clearly was - that's the law. We have this irony that the Crown solicitor at Auckland (Dickey) says the law doesn't matter when it comes to underage sex, but the law is all that matters when it comes to Mr Dennis.

"I certainly know that it's the present law that a 17-year-old can't have sex with a 15-year-old," Bonnar said.

With the boy's family growing more upset, Dennis, a family friend and the police national Maori strategic adviser, organised a "mock arrest" to scare the teen off the relationship, the court has heard.

The 17-year-old was processed at the Auckland Central Police Station on May 5, 2015, as though he had been arrested by Dennis and Perry, the duty custody sergeant.

The teen's mum and grandfather were also at the station, seemingly endorsing the mock arrest, the court has heard.

The teen told the court during his testimony: "[Dennis] said to me I could either go to Australia or, option two, he would take me downstairs and I'd be charged for statutory rape.

"At the time [Dennis] said I'd serve a minimum of 14 years. At that point I was really scared."

Every New Zealand citizen when arrested is afforded the right to talk to a lawyer without delay, refuse to make a statement to police, be told why they are being questioned, detained, or arrested, be treated humanely, and be brought before a court as soon as possible.

Dickey said the teen was not under arrest, and there was no lawful basis for him to be detained.

"You heard yesterday that [the teen] was referred to as a criminal. Now with the greatest respect, that isn't going to help you," he told the jury.

"It is perhaps the indication of the subjectivity that Mr Dennis brought to these matters."

Bonnar argued that the Crown had portrayed the complainant as a "frightened little boy", but he said the teen was an adult under most laws, does "what he wants, not matter what", and lied under oath during the trial.

Vaughan Perry was a community constable in Blockhouse Bay. Photo / Amos Chapple

After spending time in the cells across the hall from a rapist, the teen said Dennis led him back to the interview room where a discussion was held about a flight the next morning to Australia.

Agreeing to leave rather than face criminal charges, the teen was escorted to Auckland Airport and placed on a flight to Sydney.

Under the Immigration Act a New Zealand citizen cannot be deported to another country at any time.

"Mission accomplished - he has broken [the teen], the 17-year-old Maori lad. Is this the [police policy] turning of the tide? Is this policing in action? Job done," Dickey said.

Dennis said during his police interview that he was acting in line with police strategy to keep young Maori out of prison, a policy known as the turning of the tide.

Bonnar said his client's very role with police is to help Maori youth and Maori offenders.

He said Dennis "deals with people with respect and heart" and simply wouldn't trample over the rights of a young man.

"[It is] completely contradictory and inconstant with the way this man acts in life," Bonnar said.

"Please remember that this man does not have to prove a thing," he told the jury, pointing towards Dennis behind him.

On June 10, 2015, the teen decided to "escape" Sydney and return to New Zealand.

However, Dennis "swung into action", the court has heard, and contacted the officer in charge at Auckland International Airport.

He arranged for armed police to usher the teen off the aircraft.

"'What are you doing back here, you're not meant to be back here until I tell you to come back. You are to go to Australia and live your new life - how many times do I have to tell you this?'" the teen said Dennis told him at the airport.

Under New Zealand law a citizen cannot be stopped from returning home.

Dennis placed the boy on another flight back to Australia, the court has heard.

"Several police officers ought to have done better. There were enough red flags," Dickey said.

After returning to Sydney, the teen claims he was assaulted and fled to friends of his girlfriend's mum.

He then reported the scenario to New South Wales Police.

"Emotions have run too high. And it's just a shame that these emotions weren't brought down to somewhere that was more reasonably from the people that the family had turned to for assistance," Dickey said.

He said Dennis' actions could be described as "poor policing", which "takes us into the realm of an abuse of power and authority".

Dennis, who belongs to Rongowhakaata and Ngati Porou iwi and was also the chairman of Te Puea Marae in Mangere, was stood down from his duties in September 2015.

 - NZ Herald