Medical experts are appealing to the Northern Territory Government to address a law that sees mentally impaired people kept in jail indefinitely, without being convicted.

Alice Springs has an acute lack of mental health facilities, so high-needs clients end up in jail.

Four men are currently being held in the Alice Springs jail without being convicted of a crime and with no release date because they were deemed "unfit to plead".

It is a practice that has been described as tantamount to torture.

Two of them, Kerry Mandaway Doolan, 23, and Christopher Leo, 31, are being held in the maximum security section of Alice Springs prison because the Territory has no other facilities for them.

Mr Doolan has been in jail for four years without conviction, while Mr Leo is coming up to his fifth year.

Both men are thought to have been born with foetal alcohol syndrome.

Kerry Doolan was born in Mutitjulu in 1989. His mother sniffed petrol while he was in the womb.

His parents could not manage his foetal alcohol syndrome and he was abandoned in Alice Springs.

At the age of five his aunty Kathleen Wallace fostered him, along with 38 other children.

"[His parents] were drinking and forgot all about him. He was at the shopping centre all by himself," she said.

"What was he like as a child? Well, I knew he had a disability. He couldn't talk much but we made him talk."

Mr Doolan was put in jail after he threatened his carer, but he was found unfit to plead.

His lawyer Mark O'Reilly says the only response was to "warehouse" Mr Doolan and keep him in the prison system.

Mr O'Reilly described the situation as "disturbing".

"He is charged with an assault - that has been through the court," he said.

"He isn't fit to plead either. In that case it was only threatened force - no physical assault."

Inappropriate custody

Alice Springs inmate Christopher Leo, who has been in jail since August 2007. ( ABC )

Christopher Leo found himself in jail after he assaulted a woman in 2007.

Nearly two years after Mr Leo went to jail, Justice Brian Martin conducted a review hearing in which he strongly criticised the Territory Government for not providing an alternative to prison.

He expressed deep concern that had Mr Leo been able to plead, he would have only received a 12-month sentence for the assault.

"Custody in jail is quite inappropriate for people like Mr Leo, and they cannot receive the necessary treatment and support that should be available to them. The need for that facility is acute," he said.

"If I had been sentencing Mr Leo under the Sentencing Act after making allowance for the plea of guilty, I would have fixed a term of 12 months imprisonment."

Dr Larry Cashion did a neuro-psychological assessment of Mr Leo in 2008 for the courts.

"I was quite distressed for Mr Leo and I wrote a psych report after seeing him and I made very strong recommendations in that report to say that it was not appropriate for Mr Leo to be in prison," he said.

"I understood why he was there but I also said, in my opinion, his mental health was going to deteriorate markedly if he remained in prison against his wishes."

Dr Cashion says he was under the impression his 2008 recommendations would be implemented.

"It was my belief that if he was appropriately monitored and supervised and living in a dry community, as he expressly wishes, there would have been a very good chance he could live in a community," he said.

"Under these laws a lot of them have committed low-level offences. And whether they have brain damage or low intellect, they understand they are being held against their will in these facilities."

The Territory's Deputy Chief Minister, Delia Lawrie, told Lateline there is a total of six people deemed unfit to plead in Northern Territory jails.

Ms Lawrie says are also another three people in community care with 24-hour supervision.

She says the placement of the detainees is based on expert advice as to whether they are a threat to themselves or the public.

"The people who are currently in jail obviously are considered either a harm to themselves and a harm to others, which is why they're incarcerated, otherwise they wouldn't be," she said.

New complex

Sorry, this video has expired NT Deputy Chief Minister Delia Lawrie discusses the new mental health facilities.

One of the Territory's answers to the dilemma of having the mentally impaired in prison is a complex next door to the Alice Springs jail.

The safe and secure facility will be opened in the next few months. It will house eight adults and eight young people.

Ms Lawrie says a similar facility will also open in Darwin, as well as a specialist forensic health facility that will open in 2014.

"We need to obviously make clinical decisions about getting people into these more appropriate facilities and they'll be based on expert advice," she said.

"We've had experts in disability services advise the Territory Government on the model, experts from across the New South Wales, Queensland and Victoria.

"What we've done is invested in secure care facilities so that they can be moved into the secure care environment through a clinical-disability cognitive-impairment health model so that they can then therapeutically, ultimately, go into the step-down into the residential environment."

But there are already concerns that the Alice Springs facility is grossly inadequate for the current and future needs of Central Australia.

Ian McKinlay was a police officer at Papunya in Central Australia in the 1970s and 80s. He now looks after several mentally impaired prisoners in the Alice Springs jail.

Mr McKinlay says is concerned about all of them, but especially Mr Doolan and Mr Leo.

He says the new facility is marginally better than a prison, describing it as "ill-informed and primitive" compared to the therapies that are available and needed.

"My main fear is that they will continue to deteriorate; they will be out of reach of these therapies that could help them," he said.

"While they are in prison, more harm is being done and that is my firm belief."

Mr McKinlay says leaving prisoners like Mr Leo in prison with no release date is "heartbreaking".

"That would be torture for him. For an Indigenous person to be kept in that type of environment, not to be able to get out to country and family, that would be as cruel as you can get," he said.

"It is a heartbreaking thing to see. He is bewildered and he doesn't understand why he is there."

'Wave of need'

Dr Cashion says the facility's location and design are a problem.

"In my view it won't help the problem at all. It isn't part of the community and it is next to the jail, certainly to the inmates it will feel like a jail," he said.

There is also concern this new facility could act as a holding cell because of a lack of supervised community places for inmates to make a transition into the outside world.

And there are concerns it will not cater to a growing number of adults in the Northern Territory who need disability services.

"There is an unknown wave of need that is going to be hitting Australian health and welfare systems in coming years," Mr McKinley said.

"I believe this is just a vanguard of that wave of young people that have been affected ... having no effective services throughout their childhood and we are now allowed to default to the criminal justice system."

Mr McKinlay says it is time for the Health Minister in the Northern Territory to respond to the issue.

"I have been for the last three years trying to get to get the Health Minister and all Cabinet to meet and discuss this issue and to look at other models of disability support," he said.

"But they haven't been willing to meet at all - only once in the early days."