On a Monday night in July last year, the country's collective conscience was rattled by the ABC's Four Corners report, Australia's Shame.

Two images will stick in the minds of many: six boys being tear-gassed in the confined back cells of Darwin's Don Dale youth detention centre, and a young man sitting alone and restrained in a mechanical chair with a spit hood covering his face.

That night, Australia's shame cut through lounge rooms across the country and reached the highest levels of power.

The Prime Minister summed up the nation's feelings the next morning, saying he was "shocked and appalled", and he immediately acted, calling the Royal Commission into Youth Detention and Child Protection in the Northern Territory.

"We need to expose the cultural problems, the administrative problems that allowed this type of mistreatment to occur," Malcolm Turnbull said.

"We want to know how this came about, we want to know what lessons can be learnt from it."

Tomorrow, Australians will get that opportunity when the royal commission delivers its final report, which many hope will be a roadmap to change a badly broken system.

The much-anticipated recommendations have been delayed three times, and have come with a price tag of $54 million.

Caged animals

Sorry, this video has expired Dylan Voller testifies at NT child protection royal commission

Since hearings began 14 months ago, Commissioners Mick Gooda and Margaret White have heard evidence from 214 witnesses, received 480 witness statements, 320 submissions, and gathered information from across the Territory, interstate, and internationally.

Frightening statistics have bubbled to the surface: 94 per cent of young people in detention in the Territory are Aboriginal, and their numbers have more than doubled in 10 years.

At the start of the commission's hearings late last year, the boy beneath the spit hood, former Don Dale detainee Dylan Voller, spoke publicly for the first time.

"I was getting dizzy from panicking," he said about being restrained in the chair.

"The feeling of not being able to do anything, those officers could have done anything to me for that three-and-a-half hours and I wouldn't have been able to do anything about it."

He said he vomited in his mouth while hooded, and wet himself.

"Being put in a restraint chair was one of the scariest things that's happened to me, that and the tear-gassing," he told the commission.

At the time of the tear-gassing in 2014, five boys had been locked in the confined back cells of Don Dale for between 15 and 17 days after trying to escape. There was no running water, no air-conditioning, little natural light, and the cells were filthy.

"When I was in the back cells I felt like I was going mad. I would bang on the bars of the cell like I was a caged animal, a monkey," one former detainee told the commission.

When former Don Dale general manager Russell Caldwell gave evidence to the commission, he conceded there was no legal basis for keeping detainees in isolation for more than 72 hours. The rules had been bent to deal with high-risk detainees during an accommodation crisis in the centre.

"I couldn't say 'damn the consequences' and just let them out," Mr Caldwell said under questioning.

"Instead you said 'damn the law', didn't you, Mr Caldwell?," asked barrister Felicity Graham.

"No," he replied.

Systemic failure

Conan Zamolo said he became complacent and casual in his dealings with detainees. ( Suppled: NT Royal Commission )

It became clear throughout the hearings that youth detention in the NT was indeed in crisis by 2014.

It was encumbered by burgeoning detainee numbers, failing infrastructure, poor management, insufficient programs and activities for detainees, poor staff recruitment, lack of training, and a lack of oversight.

Multiple witnesses described the recruitment of tough-guy body builders into youth justice officer roles at Don Dale, and said rules were regularly broken or unenforced.

Former detainees and guards described food, water, and toilet breaks being withheld as a form of punishment.

A panel of four former youth justice officers told the commission of a "boy's club" mentality where guards enjoyed watching detainees suffer and verbally abused them.

"Oxygen thieves, waste of space, poofters, camp dogs ... it was horrible, really bad," former guard Eliza Tobin said of the name-calling.

"That was on a good day," added former colleague Louise Inglis.

Guards also complained about a lack of emphasis on de-escalating situations or empathising with the inmates.

Bigger incidents — like riots, escapes, the tear-gassing, the use of restraint chairs — could almost always be traced back to small issues exacerbated by inexperienced staff and highly volatile young people confronted with a perceived injustice: a racist taunt from a guard, recreation time cut short without

explanation, Christmas leave to visit family cancelled without reason.

Sorry, this video has expired Explicit video shows Don Dale guard asking child inmates for oral sex

'You could see violence in their bodies'

Some of the most penetrating evidence during the commission came from the statements of 24 vulnerable witnesses who had been through the system.

Their stories almost always started with family tragedy or dysfunction, followed by acting out and substance abuse, ultimately entering a downward legal spiral they couldn't fully comprehend.

They all spoke of being disconnected from family, culture, and country, and the importance of having Aboriginal staff at care centres and in detention.

"They understood our relationships with our country, I felt like they understood my sadness of being so far away from my community," a witness known as AU said in his statement.

"Most of the other guards were no good, you could see violence in their bodies and they always had bad emotions. It felt like they were angry on the inside and they would be angry at us kids because of that."

Many Aboriginal detainees spoke of being disconnected from family, culture, and country. ( ABC News: Eleni Roussos )

The inadequacy of some staff was most exemplified by the behaviour of former guard Conan Zamolo, who uploaded videos of his exploits to social media which were later played to the royal commission.

"Who wants to suck my dick? Which one of you boys wanna suck my dick?" he can be heard saying on one video after bursting into a cell late at night. In another, he filmed a detainee urinating while calling him a "gay dog".

It was language that appears to have been acceptable in the context of Don Dale.

During the hearings, former corrections minister John Elferink was shown a 2015 email he was sent in which his chief of staff said: "It is time the public knew what little c***s these kids are".

Barrister Felicity Graham pressed him for an explanation.

"What I suggest to you is that that email correspondence reflects a culture within your office that tolerated — moreover promoted — a public demonisation of young people to whom you owed a duty of care," she said.

"I disagree with that," he replied.

A trail of inaction

Former minister John Elferink conceded Don Dale was "run down" and "unsuitable" for youth. ( AAP: Neda Vanovac )

In his evidence, Mr Elferink conceded the Don Dale centre was "run down" and "unsuitable", but passed the buck to his NT parliamentary colleagues, who were unwilling to fund improvements or a new facility.

Former corrections commissioner Ken Middlebrook spoke extensively about the chronic state of under-resourcing of the youth justice portfolio by successive Labor and Country Liberal governments, describing making "application after application after application" for something to be done, only to get knocked back.

Corrections was "struggling for money", he said, a situation made worse by an ever-increasing tough-on-crime mentality of the ruling Country Liberals, and a demand to find savings of $13 million over the 2014-15 financial year.

The man ultimately answerable during some of the worst periods in youth detention was former chief minister Adam Giles; during his first hour of evidence, Mr Giles said more than 60 times that he "did not recall" or had "no recollection" of being briefed about a range of issues.

Former chief minister Adam Giles denied repeatedly any knowledge of a range of issues. ( Supplied: Royal commission )

But a 2014 memorandum prepared by the director of the Department of Correctional Services' professional standards unit showed that the problems were well known, highlighting all the issues raised during the commission's hearings.

"It should be obvious to anyone that if you treat youths like animals by not communicating, threatening, belittling them, withholding food and other entitlements, they will react in an aggressive way," it concluded.

But these systemic failures were known long before Mr Giles came to power, and ultimate blame lies at the feet of successive governments on both sides of politics.

There have been up to 50 earlier reports and inquiries on the issues covered by the royal commission's terms of reference, said counsel assisting the commission Peter Callaghan SC in his opening address.

"It invites the question as to whether there is a need to confront some sort of 'inquiry mentality', in which investigation is allowed as a substitution for action, and reporting is accepted as a replacement for results," he said.

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Punishment versus rehabilitation

The commissioners have already determined that the current youth detention system "is likely to leave many children and young people more damaged than when they entered".

Their interim report released in March signalled an intention to recommend a complete overhaul of the system, one based on rehabilitation and genuine engagement with Aboriginal people.

Investment in crime prevention, early intervention, diversion programs, and community engagement will make the community safer, it said.

Royal Commissioners Mick Gooda and Margaret White at Don Dale. ( Supplied: NT News/Elise Derwin )

Many different models have been suggested, and it's likely a combination of small to medium-sized treatment-style facilities for various levels of offending will form the backbone of a broader system.

Underpinning that, the child protection system is also in line for a major overhaul; the royal commission squeezed the issue into the three final weeks of its hearings, raising yet more terrible statistics.

The NT has Australia's highest rate of youths receiving child protection services, three times the national average. Of those in out-of-home care, nine out of 10 are Aboriginal.

The number of combined notifications, substantiations, and out-of-home placements has doubled in 10 years, Professor Sven Silburn from the Menzies School of Health Research told the commission.

"The current system is clearly not sustainable," he said.

Of particular concern are the high numbers of children in expensive emergency care, and the lack of Aboriginal kinship care available, something advocated by many in the field.

Mick Gooda and Margaret White in a cell at the old Don Dale youth detention centre. ( Supplied: NT News/Elise Derwin )

Report must not be shelved: commissioners

We will discover on Friday exactly what the royal commission sees as the way forward; then it will be up to Government to respond.

The NT Government has already signalled it will be unable to fund the changes, and Commonwealth help will be needed. The total bill will be significant.

Perhaps spending $54 million on a royal commission has given the Government a political mandate to effect and fund the necessary changes, to steer away from the "tough on crime" measures proven to be electorally popular but ineffective.

It's something to which the commissioners have obviously given some thought, as they wrote in their interim report: