Action, not repetition is needed following the announcement of a landmark inquiry into youth justice, the National Network of Incarcerated and Formerly Incarcerated Women and Girls says.

On Wednesday, the Australian Greens successfully established a Senate inquiry into youth justice and detention systems across the country, which would examine federal responsibility for youth justice.

It comes in the wake of the deaths of two young Indigenous people in less than a year in youth detention in Western Australia - 16-year-old Cleveland Dodd at Casuarina Prison's Unit 18 and an unnamed 17-year-old boy at Banksia Hill - sparking outrage and calls for change.

The National Network's Debbie Kilroy said while attention on youth detention was welcome, another inquiry left them "feeling tired and cynical".

"We have seen these inquiries before, and they invariably fall short," she said, highlighting the 10 "lukewarm" recommendations in the inquiry into murdered and disappeared Indigenous women and children.

"What we need is action, not repetition. Even in proposing this new inquiry, the language used by the Greens—terms like 'youth' and 'detention'—reflects the euphemistic vocabulary of the carceral system. It downplays the severity of the violence perpetrated by the State.

"Let's be clear: we are talking about children in prisons. The use of softer terminology shields the reality that these facilities function like adult prisons, subjecting children to environments of violence and harm."

The ongoing inquest into Cleveland's death has heard he was locked in his cell for more than 22 hours a day for 77 of the last 93 days of his time in Unit 18 before his death.

Evidence has highlighted a series of "grievous lies" told to the public by former Department of Justice director general Adam Tomison about staffing issues and conditions inside Unit 18, while former President of the WA Children's Court, Denis Reynolds, described the justice department as "incompetent" and with "no will" to change.

Furthermore, there were no cells to monitor those at highest risk of suicide and nurses were not present around the clock, a point conceded by then-deputy commissioner Christine Ginbey as "unsafe".

In Victoria last year, teachers at the state's largest youth prison raised concerns about the "rampant" use of isolation.

Some children had resorted to threatening suicide in order to be put on constant observation in order to have someone to talk to.

In Queensland this year, a report highlighted the death of two intellectually disabled Aboriginal children in the immediate wake of them leaving youth prison, where they had spent significant periods of time in isolation, resulting in one youth expert to exclaim that "no one cares".

The National Network said there was no time for equivocation, with "bold, decisive and swift action" needed.

"If this inquiry is to be genuinely useful, it must confront the root causes of the problem," said Network member Tabitha Lean.

"We must be willing to lift the veil on the criminal legal system and its failings. This inquiry must radically rethink justice so that our children are kept where they belong—in our homes, our communities, and our schools, not in cages."

The inquiry comes only weeks after the tabling in Federal Parliament of the National Children's Commissioners report 'Help way earlier!' How Australia can transform child justice to improve safety and wellbeing'.

It outlines in detail the state of the justice system for children in Australia and makes the case for reform that is based on evidence and human rights while calling for child justice, safety, and wellbeing to be made a national priority.