Western Australia's Aboriginal Legal Service is seeking a judicial review of continuing lockdowns at Perth's troubled Banksia Hill juvenile detention centre.
The application, listed for hearing in the Supreme Court on Friday, also cites concern over a special unit at the adult Casuarina Prison used to detain a small group of teenagers.
It comes after Supreme Court Justice Paul Tottle ruled in August that a teenage boy was unlawfully locked in his cell for up to a day at a time at Banksia Hill.
Justice Tottle found the boy's treatment was not authorised under the Young Offenders Act, despite the facility's problems with inadequate staffing.
He described such confinement as severe and said it could result in considerable harm.
The Aboriginal Legal Service says it represents three youths who are bringing the latest action.
They have instructed the service that they have experienced ongoing lockdowns, despite Justice Tottle's ruling.
They claim their mental health has deteriorated and that they have been increasingly distressed, leading to self-harm and suicide attempts.
The youths have also complained of excessive use of force and verbal abuse from prison officers.
Legal services director Peter Collins said repeated attempts to raise its concerns with the government about conditions in youth detention continued to fall on deaf ears.
"The breathtaking failure by the government to respect Justice Tottle's decision and its continued treatment of young people in a cruel, inhuman and degrading way is a blight on WA and needs to immediately cease," he said in the legal service's latest newsletter.
"It requires little to realise that locking a young person in a tiny cell with no television, radio, fresh air or human interaction for days on end, with all the boredom and resentment that inevitably engenders, is never going to get a result, will do nothing to change young lives for the better, and will not make the community safer in the long term."
Mr Collins said the government should abandon its current approach and embrace and resource a holistic, culturally appropriate and trauma-informed therapeutic model of care for young people in detention.
In his most recent comments, Premier Mark McGowan said his government was doing more to reform youth justice than previous administrations.
Last month, the premier also hosted a summit to discuss issues at Banksia Hill, including the use of dangerous restraint techniques, repeated lockdowns and increased self-harm incidents.
