A large proportion of Australia's prison population are there primarily because of their cognitive disability, a royal commission has been told.
An eight-day hearing of the Disability Royal Commission will hear from 33 witnesses as it explores indefinite detention and the "cycling in and out" of prison by people with disability.
"Is the justice system being used as a de facto disability service, one that proceeds by punitive rather than therapeutic measures?" senior counsel assisting, Kerri Mellifont asked during her opening statement on Tuesday.
A witness with an acquired brain injury who went from victim to offender to advocate will tell commissioners that had someone helped her find a way out of her situation earlier it could have made a profound difference to her life.
"After her release on parole, she was homeless and without support," Dr Mellifont said.
"Gradually she found her way, though. The first step was finding accommodation provided under a community government initiative."
Evidence will be presented to the inquiry to provide contrast to the idea that "ever harsher penalties and longer periods of incarceration" is the best way to promote community safety.
"If we want to promote both community safety and the human rights of people with cognitive disability, we have to challenge some of the assumptions underlying the populist view of the criminal justice system," Chair Ronald Sackville said of one of the objectives of the hearing.
He cited an Australian Institute of Health and Welfare survey that found 29 per cent of prisoners reported a long-term health condition or disability that affected everyday life.
Of those, one third of non-Indigenous entrants rated their condition as profound or severe.
For First Nations entrants, the percentage was close to half.
"The same survey showed almost one in four prison entrants were currently taking mental health medication," Mr Sackville said.
