Prime Minister Malcolm Turnbull has praised the Coalition's border security arrangements following a judgement from the High Court backing the current policy.

Key points: Majority of court's bench found current Government arrangements valid under Constitution

Majority of court's bench found current Government arrangements valid under Constitution Advocates back calls to allow dozens of children currently in Australia to remain

Advocates back calls to allow dozens of children currently in Australia to remain Prime Minister says the current policy prevents further drownings at sea

Prime Minister says the current policy prevents further drownings at sea Sarah Hanson-Young says "sending 90 children to dangers of Nauru is child abuse"

The High Court today threw 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 and later gave birth to her daughter in Brisbane.

Lawyers for the woman argued that it was illegal for the Australian Government to fund and operate detention centres in a third country.

Mr Turnbull told Parliament the Government would consider the judgement, but noted that it upheld the existing framework as "legally and constitutionally valid".

He said that the framework had kept Australia's border secure and prevented drownings at sea.

"The people smugglers will not prevail over our sovereignty," he said.

"Our borders are secure. The line has to be drawn somewhere and it is drawn at our border."

During the High Court 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 judgement 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.

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.

Prime Minister Malcolm Turnbull said the current framework had prevented drownings at sea. ( ABC: Nick Haggarty )

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.

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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 Mr 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.

Australian Human Rights Commission president Gillian Triggs said that the decision did not release Australia from its obligations under international law.

In a statement, Professor Triggs said that under those obligations, the best interests of the children expected to be sent back to Nauru should still be the primary consideration.

"We are very concerned that returning these children and their families to Nauru would further compromise their health and wellbeing, placing Australia at risk of breaching these international obligations," she said.

"Today's High Court decision in no way requires the Government to return the children and their families to Nauru.

"The Minister for Immigration has discretion to decide whether or not they will be sent back.

"Given the risk of harm to these children and their need for ongoing medical care, we strongly urge the Government not to return them to Nauru."

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."