The testimonies of more than 500 current and former Banksia Hill detainees reinforce the recent condemnation of the centre from the WA Children's Court president, advocates say.
In January Hylton Quail granted the request of a 17-year-old boy to serve his time at Hakea Prison rather than return him to the Western Australia's only juvenile jail.
In another case, Mr Quail ordered the conditional release of a 15-year-old boy rather than return him to Banksia Hill, describing the boy's experience as "one of prolonged systematic dehumanisation and deprivation".
"It has had no rehabilitative element or effect and has been unjustly punitive," he said.
"The conditions of his detention have not met the bare minimum standards the law requires and the court expects.
"When you treat a damaged child like an animal, they will behave like one, and if you want to make a monster, this is how you do it."
National Suicide Prevention & Trauma Recovery Project spokeswoman Megan Krakouer has been working with Gerry Georgatos since 2020 on a class action for current and former Banksia Hill detainees.
"Gerry and myself have taken testimony from more than 500 people right across the state with very similar circumstances," she said.
"If there are 100 children in there, there needs to be 100 nurturers dedicated to them. 100 per cent of them come from very tough circumstances.
"Banksia Hill is not sending people out into better circumstances; we have children going back inside ten, 12, 15 times."
A Department of Justice spokesperson said improvements were underway at Banksia Hill's intensive support unit.
"While enhancements are being made to infrastructure, recruitment has been underway for some time with 40 personnel currently in training," the spokesperson said.
"This cohort of personnel will start on site in March and April, with further candidates being recruited to training courses.
"Meanwhile, a new contemporary model of care for young people in custody is under development."
Staffing shortages and repeated lockdowns have become the norm in Banksia Hill, according to reports from detainees and their supporters.