Three Hāwera police officers had more than two hours to provide medical assistance to a man who would later die in their custody, a court heard today.

It's that timeline that forms one of many issues a jury of five men and seven women will have to consider during their trial in the High Court at New Plymouth, which is set down for four weeks.

The officers - who all have name suppression - are charged with manslaughter in relation to the death of Allen Ball.

Crown prosecutor Cherie Clarke alleged the officers were grossly negligent in their duty of care to the victim and that this negligence was a causal factor in his death, thereby committing manslaughter.

The manslaughter charge relates to the officers allegedly failing to provide the necessities of life, namely medical attention.

If they had provided medical attention, the Crown alleges, it may have saved his life.

Clarke told the court how the officers were called to a family harm incident and ultimately handcuffed Ball and placed him into the back of a police car.

As he was being driven back, he began to snore. On arrival at Hāwera Police Station, Ball couldn't be woken by the officers while he was sitting in the back of the patrol car.

It eventually took six people to carry Ball into a cell in the station on a blanket.

Ball's time at the station and inside the cell was captured on CCTV; not only imagery but also sound, recording what was said by the officers.

Once in the cell, he was placed on the floor in the recovery position. He continued to snore and didn't respond to any pain-compliance techniques.

Clarke said Ball was unconscious at the time he arrived at the station and at that point should have been taken to the 24-hour Hāwera Hospital, which was just a five-minute drive away.

Clarke said Ball continued to remain unresponsive while on the cell floor.

The Crown alleges that during the time that he arrived at the station - between 11.46pm on May 31, 2019, and by the time an ambulance was eventually called at 2.26am - neither of the officers opted to call for medical assistance.

"If he had been provided medical care between 11.46pm and sometime before 2am that morning he would have survived a drug and alcohol overdose," Clarke told the jury.

As Ball lay on the floor of the cell, he was pronounced dead at 2.53am.

His cause of death was due to fatal quantities of alcohol, tramadol and codeine.

Clarke said the officers had owed Ball a duty of care given he was in their custody and that was to provide treatment in a humane manner.

The officers knew that Ball had drunk a large amount of alcohol prior to his arrest and that he had threatened to commit suicide, and all three knew that he didn't respond to subsequent pain-compliance techniques.

All three knew that Ball couldn't be woken in the car, or once placed in the recovery position in the cell.

After entering his intoxication in the police NIA system as "extreme", Officer B and C then opted to "blatantly ignore" an alert that came up on the computer screen.

That alert said to arrange for the person to be taken to hospital.

In order to continue through the NIA alert system, the officer had to click "OK", which he did.

'The idiot was f****** wasted'"

Ball was checked on many times throughout the morning by officers.

The checking involved everything from an officer looking into the cell, leaning over Ball, being kicked in the foot. The officers could also hear Ball snoring during his time in there.

Clarke also described some of the comments made by the officers, which included "the idiot was f****** wasted by the time he got here", that Ball was making "happy noises" in reference to his snoring and that he was "very 1K" which means "drunk".

By 1.05am, Ball was still unmoving on the floor, he was checked again four minutes later with Officer A nudging his foot with their own, before saying "Allen, Allen did you want a drink of water or not, eh?"

Officer B then enters the area, and Officer A makes a "horizontal gesture" under her chin before Officer B then states, "10/0 cuz, no good".

10/0 is an unofficial police term for a person being dead, Clarke told the jury.

Officer A replies, "yeah," before Officer B laughs and says "f****** hell".

At 1.11am, Officer C is heard saying "is he still alive?". At 1.24am, Officer A enters the area - but not Ball's cell - before leaving the station with another officer at 1.25am.

Ten minutes later, Officer B enters Ball's cell, looking at him for four or five seconds, and enters into the NIA system "snoring, still on his side in recovery position".

He's checked again at 1.53am, and Clarke said it would at around this time that an accident and emergency doctor will give evidence - after watching the CCTV - that it was about then that he was hyperventilating and likely in respiratory arrest.

Another officer and Officer B were seen on CCTV but neither checked on Ball.

At 2.23am, Officer C enters the cell, kicks Ball's foot and gets no response. He bent down towards the head of Ball and stayed bent over for 55 seconds saying "Allen".

Another officer then comes into the cell and says, "he's cold" before Officer B enters at 2.25am and a minute later says "get an ambo, bro".

Officer B got a defibrillator and together with Officer C and another officer they proceed with CPR.

He's pronounced dead at 2.53am.

The trial, before a jury of five men and seven women, kicked off in the New Plymouth High Court this morning.

It is being overseen by Justice Susan Thomas.

The Crown will call 24 witnesses over the four weeks the matter is set down for.

There are several supporters in the public gallery, including Police Association president Chris Cahill.