The Northern Territory Supreme Court has awarded nearly $1million in damages to four Indigenous former inmates of the notorious Don Dale youth detention centre over an unlawful tear gassing in 2014.

The four detainees were exposed to CS fogger tear gas by a prison officer in August 2014, after a violent incident broke out at the Darwin facility, which lead to a confrontation between staff and another inmate, Jake Roper, who they wanted to "temporarily incapacitate".

Mr Roper had escaped from his cell within the Behaviour Management Unit of the centre and damaged property, the court found. Guards ultimately decided to use CS gas to control Mr Roper so he could be taken into custody, deploying it in nine short bursts in the unit.

The four former inmates - Josiah Binsaris, Keiran Webster, Ethan Austral and Leroy O'Shea - were exposed to the gas after being locked in their rooms. The court found they were assaulted, handcuffed before being taken to a basketball court and "hosed down to remove any residue of gas".

Justice Jenny Blokland said the inmates received "callous treatment" at the hands of the guards in the aftermath of their exposure.

"There is a sense of grievance expressed as to why they were treated roughly, hand cuffed from behind, placed on the basketball court on their stomachs and hosed," she found.

"Given what they had endured, they deserved to be treated with more care than the callousness evident on the available footage."

Mr O'Shea, who was asthmatic, shared a cell with Mr Webster. In an affidavit he stated he feared he was going to die after the gas was deployed.

"The teargas affected me badly and from the way I saw Keiran acting, it seemed to affect him badly as well," he said.

"My throat was burning, I was choking, my eyes were stinging and my nose was running. Keiran looked like he was throwing up.

"After they sprayed the teargas, I felt complete fear. I thought I was going to die. The worst thing was not knowing how long it was going to last and how long we were going to have to sit in there and burn."

Justice Blokland said it was clear there was "high-handedness or disparaging comments on the part of some officers towards detainees."

"For example, when determining how to deal with Jake Roper, one of the officers, who is unknown, said, 'Nah, let the f***er come through because while he's coming through, he'll be off balance. I'll pulverise the little fucker. Oh shit, you're recording'," she said.

"One of the officers who was in that conversation which took place in the storeroom then said: 'Go grab the fucking gas, we'll gas him through fucking, get Jimmy to gas him through here."

The awarding of damages is the culmination of a years-long struggle to get compensation for the four plaintiffs.

An original trial judge in 2014 found the tear gassing of inmates during disturbances at the facility was legal. This decision was challenged by the plaintiffs in the Court of Appeal but was dismissed.

In 2020, the High Court ruled to uphold the appeal of the four former inmates and were entitled to compensation, meaning the decision of damages would ultimately be deliberated on by the NT Supreme Court.

Justice Blokland ruled on the damages, to be paid by the NT government and totalling $960,000.

Mr O'Shea is entitled to $250,000; Mr Binsaris is entitled to $220,000; Mr Webster is entitled to $250,000 and Mr Austral is entitled to $240,000.

"The awards to be made for general and aggravated damages will be appropriate for the amount of time the plaintiffs were subject to mistreatment constituting battery and its associated distress, physical and psychological," Justice Blokland said.

"The conditions which gave rise to this unlawful use of force perpetrated on youths in a detention centre for whose safety and wellbeing the defendant was responsible for must never be allowed to happen again.

"I accept the difficulties the youth justice officers experienced; however, the defendant must take responsibility for putting them in that position or creating the conditions where they thought they had no option but to resort to unlawful unreasonable and excessive force."

Justice Blokland said the incident "must never be allowed to happen again".

"Young people in custody must be protected from exposure to such danger. This is fundamental. The court must demonstrate its disapproval of the Northern Territory allowing this to take place," she said.

In awarding damages, she said the plaintiffs were ultimately bystanders, and youths who were under the ultimate supervision of the state.

"They were treated as though they were the troublemakers," she said.

"The incident as a whole shows the plaintiffs were treated in a manner which recklessly disregarded their rights and interests.

"Senior officers working in a youth custodial situation should never have been placed in a situation where they thought it was lawful to use a weapon when it was not."

The NT government argued it was irrelevant that the four inmates were Indigenous, something Justice Blokland disagreed with.

"The fact the plaintiffs are Aboriginal is a factor. Unlawful actions by any arm of law enforcement, including Correctional Services, towards Aboriginal people adds to alienation and disengagement from the broader community for complex reasons which for many, but not all Aboriginal people, continue to resonate."

The NT government has three weeks to pay the damages.

Graphic footage shown on ABC TV in 2016 of the four detainees being tear-gassed led to a 2017 Royal Commission into the Protection and Detention of Children.

The NT government accepted in full or in principle all 227 recommendations with an estimated cost of $229 million.