Youth incarceration shouldn't be seen as a last resort, but one we "actively resist," leading human rights lawyers and Indigenous legal and policy experts have said.

In a joint submission to the parliamentary inquiry into Australia's youth justice and incarceration system, the National Justice Project and Jumbunna Institute for Indigenous Education and Research said the mistreatment of young people in custody - especially First Nations youth - is rooted in systemic failures, which have had a "devastating impacts not only on the young people detained but also on their families, communities, and future prospects".

National Justice Project chief executive, Adjunct Professor George Newhouse, said Australia was witnessing prisons become the "ad hoc response to youth in desperate need of more appropriate care and support".

"The system disproportionately affects First Nations youth with a pressing need for a transformative approach that prioritises the wellbeing and development of young people over punitive measures," Professor Newhouse said.

Long criticised for its "inadequate treatment of detained young people," the submission highlighted Banksia Hill Youth Detention Centre, which recently saw the second young person die in custody in WA in less than a year.

"Youth detention centres, at present, are not fit for purpose and undermine young people's social, cultural, and educative development. Banksia Hill reveals a consistent pattern of mistreatment and systemic failure that affect all areas of detained young people's lives," it said.

The submission argued the intersecting degree of compliance and non-compliance by state, territory and federal prisons and detention centres regarding the human rights of children and young people in detention; and the Commonwealth's international obligations regarding youth justice - including the rights of the child, freedom from torture and civil rights - urgently need to be addressed.

"Any genuine reform must centre on these intersections and incorporate the resilience and cultural importance of First Nations communities," it stated.

The submission highlighted a lack of education, connection to culture, access to health services and the impacts of lengthy periods of isolation on children in youth justice, many of whom come out traumatised and more likely to reoffend.

On children in isolation, the submission identified young inmates spending 24 hours a day for lengthy periods of time, alone in their cells at Unit 18 in Perth's maximum-security Casuarina Prison.

"The psychological impact of such isolation is profound, leading to deteriorating mental health, increased feelings of hopelessness, and heightened risks of self-harm or suicide," it stated.

Last year, the Supreme Court found youth detainees at Banksia Hill were subjected to unlawful confinement on a "frequent basis," with Justice Tottle describing the situation as a "systemic failure".

The ongoing hearing into the death of 16-year-old Yamatji boy Cleveland Dodd - who died after being found unresponsive in his cell in Unit 18 - has revealed the lack of political will to help children in youth custody.

The inquest has heard a series of lies, misinformation and lack of care was evident surrounding youth justice in WA.

Former President of the WA Children's Court, Denis Reynolds, described the justice department as "incompetent" and with "no will" to change, and said the former Minister Bill Johnston and Premier Mark McGowan "were to the detriment of community safety; they were pushing the demonisation of the children".

In Queensland earlier this year, National Indigenous Times reported two disabled Aboriginal boys, who spent the majority of their time in solitary confinement, died in the immediate aftermath of leaving youth detention.

Jumbunna's Director, Professor Lindon Coombes, said the inquiry is a first step in addressing the historic and continual mistreatment of young people in custody—particularly First Nations youth.

"The overrepresentation of First Nations youth in detention is a clear issue, where the harm caused extends far beyond incarceration, perpetuating cycles of trauma and disadvantage across generations," he said.

They submitted that a transformation in youth justice needs investment in diversionary programs, culturally appropriate community and family care, as well as community-focussed preventative measures.

"Focus must shift to community-led, preventative measures, especially for First Nations young people," it said.

"By investing in early intervention, mental health services, and culturally appropriate community care, we can address the root causes of young people offending and reduce the need for detention altogether."

Highlighting the prevalence of at least one psychiatric disorder in up to 73 per cent of all youth detainees – with the numbers even higher for First Nations young people – it also called for culturally appropriate, trauma-informed mental health services to be delivered within communities rather than through the justice system.

This, they said, is essential to preventing further harm.

"First Nations community-led organisations are best placed to deliver these services, as they understand the unique social, cultural, and emotional needs of First Nations young people," it said.