The lawyers challenging the constitutionality of the Australian detention centre on Papua New Guinea's Manus Island say they are seeking to invite the asylum seekers there to join the legal action.
One of the lawyers acting on behalf of PNG's opposition leader, Belden Namah, said on Wednesday he had received instructions to ask the asylum seekers to join the application against the centre.
Mr Namah's lawyer, Loami Henao, said they were seeking permission to visit the temporary detention centre on Manus to interview detainees for this purpose.
The lawyers were also seeking a temporary injunction in the Court of Human Rights of the National Court against any further transfers on the grounds the 274 detainees were being held illegally under PNG's constitution.
Justice David Canning said he would rule on the temporary injunction at midday today.
The government's lawyer, Peter Kumen, said the Migration Act gave Minister of Immigration Rimbink Pato the power to create a processing centre.
He also argued that the case was a matter for the Supreme Court, and not the National Court circuit.