The High Court has thrown out a challenge to the Australian Government's immigration detention centre on Nauru.
The case was launched by a Bangladeshi detainee on Nauru who was brought to Australia for treatment after she experienced health issues during pregnancy.
She gave birth to her daughter in Brisbane, and brought the challenge to avoid being returned to the detention centre.
Lawyers for the woman argued that it was illegal for the Australian Government to fund and operate detention centres in a third country.
During the case the Government changed the law to close a loophole in the funding arrangements, which it feared could be undermined by the challenge.
Today a majority of the court's bench found the current government arrangements were valid under the constitution.
Justice Michelle Gordon, the most recent appointment to the bench, issued the lone dissenting judgment that the laws rushed through in June were invalid.
Before the decision, Immigration Minister Peter Dutton flagged his intention to send a group of 160 adults, 37 babies and 54 children currently in Australia back to Nauru, should the Government win.
One of the children facing return to Nauru is a five-year-old boy allegedly raped at the detention centre, but Mr Dutton has said he will take concerns from doctors about the boy's welfare into consideration.
The boy's alleged attacker remains at the centre.
The lawyer leading the case against the Government, Daniel Webb from the Human Rights Law Centre, has criticised the Government for changing the law while the challenge was underway.
Mr Webb said they "shifted the goalposts".
"Right now, I'm sure in the Immigration Minister's office it's high fives all round," he said.
"They won in the High Court, but let me tell you, around the country right now there are 267 incredibly vulnerable people who will be terrified."
Mr Webb urged the Government to allow the detainees to remain in Australia.
"Our government retains both legal and moral responsibility for what happens to innocent people in our care," he said.
"The stroke of a pen is all that it would take for the Prime Minister or our Immigration Minister to do the decent thing and let these families stay."
Decision to send families 'back to hell' lies with PM: Ludlam
A similar case questioning the validity of offshore detention also failed in 2014, however that case did not challenge the legality of Australian operation and funding of offshore detention centres.
Comment has been sought from Mr Dutton.
Responding to the judgement, Deputy Labor leader Tanya Plibersek said the focus would remain on regional resettlement if Labor was elected to government.
Ms Plibersek said reports of abuse within the centres were troubling, but advocated for improvements — rather than an end — to offshore detention.
"There's no excuse for the fact that processing times have doubled under this government," she said.
"It's also worth saying that our preference while we were in government was an arrangement with Malaysia. It would have allowed people to live and work in the community."
Shadow Attorney-General Mark Dreyfus earlier stated the policy of offshore detention should not necessarily be abolished altogether.
"I don't think it's necessary to say that, that it's time to end that policy," he said.
The former Labor government was responsible for the re-establishment of offshore detention on Nauru, as well as the introduction of a facility of Manus Island.
Greens senator Sarah Hanson-Young has already responded to the judgement on Twitter, saying that "sending 90 children to dangers of Nauru is child abuse".
In a statement, Senator Hanson-Young called on Prime Minister Malcolm Turnbull to rule out sending children and their families back to Nauru.
"It's undeniable that Nauru is unsafe for women and children and sending them back would be torture," she said.
"This is the first major test for the Prime Minister.
"Will he keep these children safe, where they can thrive and prosper, or will he dump them back on the prison island of Nauru?"
Her colleague senator Scott Ludlam has backed her comments, saying that the decision of whether to "send children and families back to hell" lies with Mr Turnbull.
Calls for Prime Minister to 'show compassion'
Advocates have backed the Greens' call and urged Mr Turnbull to allow dozens of children currently in Australia to remain.
Save the Children's Lee Gordon — formerly responsible for the direction of welfare, education and recreation services for children and adults at Nauru — said the families were currently living in limbo.
"I know from experience the devastating psychological and physical harm that is caused to asylum seekers and refugees living on Nauru," he said.
"We call on Prime Minister Turnbull to act with compassion and request the Department of Immigration and Border Protection to quickly process the asylum claims of the people impacted by today's High Court ruling.
"If found to be genuine refugees, we urge him to do the decent thing and offer these vulnerable people permanent protection here in Australia."
Not-for-profit group ChilOut also voiced concerns for the children, including the 37 babies born in Australia.
In a statement, ChilOut campaign coordinator Claire Hammerton said the Government knew Nauru was unsafe.
"Detention is never an appropriate environment for children, but detention in Nauru is especially inappropriate," she said.
"The centre in Nauru is particularly unsafe, with substantial evidence revealed in recent years regarding physical and sexual abuse in the Nauru Detention Centre and on the island, including against children."
Picture source: AAP