Australia's Opposition says the Government is asking it to support emergency legislation to plug a legal loophole that could see the nation's offshore immigration detention network collapse.
Ten asylum seekers are challenging the legality of the system. They have argued that, because Australia issued the contracts for the establishment and maintenance of the processing facilities, they are Australia's responsibility - not that of Nauru and Papua New Guinea.
They also argued that the necessary laws had not been passed to authorise the facilities.
A procedural hearing for the case was held in Melbourne today and a further directions hearing is scheduled for Friday.
Last year, the High Court ruled that, with limited exceptions, the Government needed legislative authority to spend public money on big policy issues.
The ABC has been told Prime Minister Tony Abbott called Opposition Leader Bill Shorten last night to ask for his help.
It is understood Mr Abbott told Mr Shorten the whole detention system was vulnerable, and could be declared illegal by the High Court during the upcoming six-week winter break unless the loophole was closed.
The Opposition said that it would support a bill to ensure the continuation of the network.
Greens Senator Sarah Hanson-Young said the Government was moving to change the law so they did not have to "face the music" in the High Court.
"For the last three years this Government and the previous government illegally detailed children and families on Nauru and Manus Island.
"Labor has got to grow a spine - stand up when it matters."
But Attorney-General George Brandis denied the Greens' claim that the urgent bill meant offshore detention had been illegal.
"No, that's incorrect ... the Government is of the view that the offshore processing arrangements are lawful," Mr Brandis said.
"The legal advice to the Government and to the previous Labor government was that the scheme was within the law."
Mr Brandis said the bill would come before parliament's upper house today or tomorrow.
The centres on Nauru and Manus Island were opened by Australia under John Howard's government, before being closed and reopened under its previous Labor government.