Aboriginal and children's rights groups are campaigning against sentencing laws that have led to youngsters being jailed after being fined for minor offences.
The groups want the laws, imposed by the Northern Territory and Western Australian governments, repealed, especially as those most likely to be imprisoned are young Aborigines.
This is despite recommendations last year by a Royal Commission that imprisonment should be a last resort - and not for children.
In the Northern Territory last year, a 15-year-old Aboriginal girl was strip-searched and spent a night in a detention centre for not paying a fine. Her crime was not wearing a bicycle helmet.
In another case a 12-year-old boy, faces three months in the Darwin detention centre for failing to pay $2,000 (pound;444) in fines - also for not wearing a bicycle helmet. Ricky was originally given a $25 (pound;10) on-the-spot fine by police which he threw away. The fines increased over three months until a warrant was issued for his arrest. His grandmother said she could not afford to pay the fines. "I feel everything is wrong with the system," she said.
In Western Australia, a "three convictions and you're in" law has led to teenagers being sent to jail but a federal parliamentary committee believes this could be in breach of the UN Convention on the Rights of the Child.