The central Jakarta District Court will this morning begin hearing a class action against the Australian Government over allegations Indonesian boys jailed for people smuggling were held in adult prisons.
With the support of Indonesia's National Commission of Child Protection (KPAI), lawyer Lisa Hiariej will argue the case on behalf of the group of 115 Indonesians, who were allegedly either jailed or held in immigration detention as juveniles.
"They are very scared, they are not criminals," Ms Hiariej told the ABC ahead of the court appearance.
"Their mental health is still not good."
Ms Hiariej alleged 31 boys aged between 13 and 17 years old were jailed in adult prisons in Sydney, Melbourne, Brisbane and Perth between 2008 and 2012 for crewing asylum seeker boats.
Ms Hiariej said a further 84 boys spent more than three months in immigration detention, which she believes was against the law.
The court will hear the children were themselves victims of people smuggling and they are seeking millions of dollars in compensation from the Australian Government.
Three judges will preside over the civil case.
"The lawyers found out they were underage by going to their villages and finding their birth certificates," Ms Hiariej said.
She said she had the 115 birth certificates to prove the case.