An urgent request to stop the transfer of a newborn baby and its family to Nauru will be heard in a federal court in Brisbane on Tuesday.
Latifar, a Rohingyan woman from Myanmar, was transferred from Nauru to give birth to Ferouz in Brisbane's Mater Hospital a fortnight ago.
They remain in detention with the child's father and siblings, Maurice Blackburn Lawyers told AAP.
Associate Murray Watt says they will seek in the Brisbane Federal Circuit Court on Tuesday to keep the family in Australia until the child's health improves.
AAP reports Ferouz remains weak, has trouble breastfeeding. His mother, who has diabetes, is recovering from a caesarean birth.
Mr Watt said it is a test case because it concerns the rights of an asylum seeker to present independent medical advice about their health, before any decision is made to take them back to Nauru.
And, he said, it raises questions on whether the government can take Ferouz to Nauru at all, given that he was born in Australia.
"This family of asylum seekers from Burma has already been poorly treated, with limited access to visit their newborn son, Ferouz, while he remained in hospital," Mr Watt said. "This is an important case."