Australia did not require Nauru to detain asylum seekers sent to the small Pacific nation for processing and any such limits on their movement had to comply with local law, government lawyers have told the high court on the final day of a hearing about offshore detention.

Australia’s solicitor general, Justin Gleeson SC, disputed assertions by lawyers for a Bangladeshi asylum seeker that Canberra was effectively responsible for the detention of people it transferred to Nauru because it paid for their temporary visas and funded the processing centre.

But Gleeson argued that even if the high court made such a finding, the actions were authorised by retrospective changes to the Migration Act that the Australian parliament passed in June, a month after the plaintiff initiated her case.

“It’s belts and braces; it’s parliament looking at what the executive [government] is doing saying, ‘If you need our permission you have it,’” he told the court during a hearing in Canberra on Thursday.

Gleeson said parliament had passed the legislation “in order to ensure that at least this aspect of the case didn’t trouble the court”.

He was addressing the full bench of the high court on the second day of a hearing into a case that challenges the legality of Australia’s involvement in the detention of asylum seekers in Nauru and the validity of the Australian government’s contract with the processing centre operator Transfield Services.

On Thursday afternoon the high court reserved its decision. The result could have broader implications for the future of Australia’s system of offshore processing, which has support from the main political parties, but a decision could be months away.

The lead case involves a Bangladeshi woman who was on a boat intercepted by Australian officers in October 2013 and was detained on Nauru from January 2014 until August 2014, when she was brought to Australia for medical treatment and subsequently gave birth to a child. The baby is now 10 months old, and they are in detention in Darwin.



The woman’s lawyers argued on Wednesday that the Australian government had “funded, authorised, procured and effectively controlled” the detention on Nauru, but this was not authorised by a valid Australian law or section 61 of the constitution.

They were seeking to prevent her return to Nauru, saying there remained a risk she would be detained there because the new “open centre” arrangements announced by the local government could be revoked at any time.

Gleeson, who began his oral arguments late on Wednesday but continued to address the court on Thursday, sought to rebut the argument about the extent of Australia’s involvement. At most, he said, the court could find that there was “substantial funding and assistance by Australia in various steps which enable Nauru to carry out its law on its soil”.

The solicitor general said Nauru was a sovereign state that could not be bound to accept people Australia transferred to the island. He conceded that an application for Nauru’s special regional processing visa could only be made by an Australian officer but Nauru determined whether to accept it and what conditions to impose.

When the chief justice, Robert French, suggested that the visa “didn’t come out of the sky”, Gleeson replied that the critical point was that Australia did not determine the conditions.

Gleeson denied the plaintiff’s arguments that detention on Nauru could be described as arbitrary, saying it was associated with the purpose of processing refugee claims and, if successful, people would “graduate to a temporary settlement visa”.

Nauru had the power to relax the requirements for people to remain in the processing centre, he said. “If an Australian official purported to give a direction to a service provider to reject a request to leave the premises the service provider would be entitled to say, ‘I’m exercising a power pursuant to Nauruan law and that must be my guiding touchstone, not simply the dictates of Australia.’”

French asked whether the commonwealth, in the implementation of the arrangements, could be taken to provide “material support necessary for the establishment and maintenance of a detention regime”.

Gleeson said: “The short answer to that is yes.”

Referring to security restraints, Gleeson said: “Our position is it’s a restraint imposed by Nauru capable of relaxation by persons Nauru chooses who operate as Nauru functionaries.”

Gleeson acknowledged the Transfield contract contained references to Australian laws and policies, but added: “Anything the commonwealth and Transfield might agree is naturally subject to the overriding force of the laws of Nauru.”

But Craig Lenehan, one of the lawyers representing the woman who brought the case, said Australia had requested Nauru to host a regional processing centre, had directed that people be taken to Nauru, and had applied for the visas “which require she reside” at the centre and which had “nothing to do with the consent of the plaintiff”. Australia had also funded centre infrastructure and had appointed service providers to run the centre.

“It’s certainly true, we accept, that Nauruan law provides the architecture for the detention; however, we say that the commonwealth requested it be part of that architecture … and can take transferees into and out of that architecture, which we say therefore leads to causing or procuring that detention,” Lenehan said in summing up the case on Thursday.

“It is not right to say … that the consequence of the plaintiff’s claim is that there’s no power to provide a form of assistance to any sort of international cooperation effort which involves some form of detention. Our claim is based on what we describe as a thoroughgoing commonwealth involvement in the detention, such that it has become a commonwealth detention.”

Transfield’s lawyers also gave evidence to the court on Thursday in defence of the validity of its contract. Stephen Donaghue QC, for Transfield, mounted a similar argument to that of the government.

“Detention, to the extent that it occurs, is a product of decisions taken in Nauru by the government of Nauru and authorised by the law of Nauru,” he said.

The case began with an application filed on 14 May for an order to prevent the immigration minister, Peter Dutton, from taking steps to return the Bangladeshi woman to Nauru.

In June the Australian government – then led by Tony Abbott – rushed legislation through the federal parliament to retrospectively clarify the commonwealth’s powers to fund regional processing centres.

The legislation – which won support from the Labor party – inserted a new section into the Migration Act, backdated to August 2012, saying the commonwealth may “take, or cause to be taken, any action in relation to” regional processing arrangements.

The new section, known as 198AHA, also declared the commonwealth could “make payments, or cause payments to be made, in relation to the arrangement or the regional processing functions of the country” or “do anything else that is incidental or conducive to the taking of such action or the making of such payments”.

Gleeson told the court on Thursday the new provisions were designed to satisfy the requirements that arose from the so-called Williams case, which related primarily to the federal government’s funding of school chaplaincy but had broader implications.

“Namely, it works on a theory that it would be within the executive power under section 61 of the constitution for the executive to decide, as it were, to enter the arrangement in the first place,” he said.

“Here is parliament saying, ‘You may go ahead and do everything you need to perform that arrangement which you’ve considered appropriate to enter.’”

Gleeson emphasised that although the legislation gave the Australian government the capacity and authority to undertake such actions, it could not override Nauruan law.

The Australian Human Rights Law Centre, which is representing the Bangladeshi woman and says it is acting for about 200 other asylum seekers who were brought to Australia temporarily, maintained that the “really important case” involved important legal questions.

The centre’s director of legal advocacy, Daniel Webb, said the case had already achieved some important improvements on Nauru, including speeding up processing and the level of freedom people had.

“But we should be clear these improvements in no way address the fundamental injustice of leaving innocent families languishing on tiny Pacific islands,” he said outside the court on Thursday.

“This is a case that has seen unprecedented retrospective changes to the law and sudden last-minute changes to the facts. Both of those things were designed, I think, to have an impact on the case and both of those things do have an impact on the case. But ultimately what impact that will be, we’ll have to wait and see for the court’s decision.”