A Tamil family could spend months in detention on Christmas Island before their deportation case is heard in court.
An order made on Thursday blocks the family's deportation until a visa fight is determined at trial.
But a court date has not yet been set for their case to be heard, with the process expected to take months.
In the meantime Priya and Nades Murugappan and their daughters Kopika, four, and Tharunicaa, two, remain in "mental torture" on Christmas Island.
"This is not the place children should be, " Priya told Sky News through an interpreter following the court decision.
"It is very difficult to live on Christmas Island. There is no proper safety here. Children feel lonely."
There was also no bathroom in the unit or access to proper toilets, she explained.
The upcoming legal trial will focus on Tharunicaa and her right to apply for a protection visa.
Her parents and sibling have already been refused refugee status, but the family is being kept together while the matter is finalised.
Despite being born in Australia, Tharunicaa would normally also be refused Australia's protection as she is legally considered an "unauthorised maritime arrival" because her parents arrived by boat.
But in a new argument aired in the Federal Court this weekby her legal team, Tharunicaa should still be entitled to apply for a protection visa following a period in 2017 when Mr Dutton "lifted the bar" for boat arrivals.
Justice Bromberg said the family had a prima facie case that Tharunicaa's visa application was valid, and until that application was finally determined, the federal government had no power to deport her.
The family had previously settled in Biloela in Queensland before they were moved to a Melbourne detention centre.
© AAP 2019