Justice John Dixon said on Thursday that the state's re-classification of Barwon Prison's Grevillea Unit as a youth justice and remand centre was "incompatible" with the inmates' human rights.

There have been reports that some of the young inmates have been kept in lock-down for up to 23 hours a day. 

The court's decision is likely to mean that the government must find somewhere to house the more than a dozen young offenders who have been held at Barwon prison.

It will also heap further pressure on Youth Affairs Minister Jenny Mikakos and the Andrews government over its handling of the youth crime crisis which has dogged it, with riots and breakouts at the Parkville and Malmsbury youth justice centres over the past year.

The state initially classified the Grevillea unit in order to move dozens of teen inmates from Parkville and Malmsbury to the unit last year, following a riot at the Parkville youth justice precinct which destroyed more than 60 beds.  

The government has argued that it had no other option but to imprison the inmates at Barwon because Parkville had been so badly damaged – repairs and extra fortification works at Parkville are not yet completed.

In the face of mounting public concern about youth crime, Labor had also said that the youth offenders that had destroyed Parkville belonged in an adult jail

Ms Mikakos told parliament that she was disappointed with the court's decision but said the government would now consider its options.

She confirmed there were 16 young offenders currently incarcerated in the Grevillea unit.

It is the third time a Victorian court has declared the move to be unlawful.

Speaking outside court after the decision was handed down, Lawyers for the children called for the government to quickly move the inmates from Barwon Prison

"The government made a mistake and it now has an opportunity to do the right thing and get these kids out of Barwon immediately," said Alina Leikin. from the Human Rights Law Centre. 

She said the children, some of whom had been at the prison for more than five months, had declined mentally and physically.

"They've missed out on education opportunities ... on family connection, and these things are critical to their rehabilitation and in the long run to community safety."

The centre's executive director Hugh de Kretser agreed, saying that repairs to Parkville would soon return some 60 beds to the youth justice system.

"The Victorian government has an otherwise good record in the youth justice system in achieving some of the lowest youth imprisonment rates and some of the lowest youth crime rates in Australia," he said.

"We now have an opportunity to move on and build a youth justice system that has age-appropriate, lawful, safe, humane facilities that promote community safety through rehabilitation."

While conceding that some of the children at the unit had contributed to the damage caused in the Parkville riot, Mr de Kretser said that many of the children sent to Barwon Prison were not involved in the incident.

In November Premier Daniel Andrews said he made "no apology" for sending up juvenile offenders to adult prison despite a damning Ombudsman's report condemning the practice as indefensible. 

Both the Supreme Court and the Court of Appeal have previously ruled that Ms Mikakos unlawfully failed to consider the inmates' legal rights when she initially classified the unit a youth justice and remand centre last year.

The state re-classified the unit in almost identical terms in December, days after the Court of Appeal – Victoria's highest court – ordered it move children detained in the unit to a lawful detention centre.

Ms Mikakos said at the time that the government's re-gazetting of the prison had taken into account the court's concerns, making the unit lawful.

Justice Dixon will make formal orders which will determine what happens next to children on Friday.

Melinda Richards, SC, for the government parties, declined to indicate on Thursday whether the state would appeal the court's latest decision, saying they would need time to consider the judge's reasons.

Shadow youth affairs minister Georgie Crozier said the decision showed what a shambles the youth justice system was under Labor.

"Jenny Mikakos has presided over a system where violent youths have been rewarded for bad behaviour with pizzas and video games which has bred a culture of disrespect, more violence and wilful damage," Ms Crozier said.

"How many more times can Daniel Andrews protect this incompetent minister?"

Greens youth justice spokesperson Nina Springle said the government needed to relocate these young people to an appropriate facility immediately.

"The abusive, cruel treatment of detainees isn't doing anything to make the community safer or rehabilitate these young people," Ms Springle said.

"The only way to rehabilitate these detainees is with proven therapeutic youth justice programs. Locking kids up in an adult prison to appear tough on crime isn't helping anybody."

More to come

More to come

The Age.