Almost three years after the 'stop the boats' election, there is a surprising lack of debate on irregular migration in Australia in this campaign. The bipartisan consensus on offshore processing appears to have removed the political incentive for any serious policy discussion. This week there were echoes of the 2013 election when Prime Minister Malcolm Turnbull warned of chaos on Australia's borders in the event of a Labor victory, but this was largely seen as a tactical move to counter Labor's scare campaign over Medicare.

The Lowy Institute's Poll this week probably validates the major parties' reluctance to engage in policy debate. The Poll showed public support for the policy of turning back boats continues, with 63% of Australians agreeing that 'stopping the boats means that Australia can take in more refugees through UN processes'. There are few votes to be won in softening Australia's hard-line stance on asylum seekers who seek to come to Australia by boat.

But Australian politicians are studiously ignoring the reality that the PNG Supreme Court's 26 April ruling that the detention of asylum seekers in Manus was illegal and unconstitutional. This will force a change to the offshore processing policy by removing a key plank of Australia's deterrence strategy in managing irregular migration.

This week the Supreme Court will hear applications for consequential orders that will enforce its decision. While government ministers can argue this process has no legal consequences for Australia, the PNG government will have no option but reiterate its plea to Canberra to relocate the asylum seekers and refugees. Australian voters deserve to hear how their future government plans to respond to this.

There is no excuse for the lack of political debate about the future of the detainees in Manus.

Prime Minister Peter O'Neill has signalled publicly he no longer has any motivation to resettle those asylum seekers found to be refugees in Papua New Guinea. He moved quickly after the Supreme Court ruling to announce the closure of the Manus detention centre and said he would ask the Australian government to make alternative arrangements for the men detained there. It seems unlikely he will endorse the suggestions of my friend Lisa-Marie Tepu and address the treatment of refugees within Papua New Guinea. Even before the Supreme Court ruling, O'Neill told Australia's National Press Club that his government could not afford to resettle the refugees and wanted to close the Manus centre.

Immigration Minister Peter Dutton tried to deflect earlier debate on the ruling by saying it was a matter for Papua New Guinea. He has reiterated government policy that refugees in Manus and Nauru will 'never' be resettled in Australia. His Labor counterpart Richard Marles concurs. Prime MinisterTurnbull said much the same on Monday night when he told the ABC's Q & A program that people who were found to be refugees in Papua New Guinea did not have the option of coming to Australia; they had to stay in PNG.

Australia says it is PNG's problem and Manus detainees will never be resettled in Australia. Papua New Guinea will neither detain nor resettle the refugees, nor accept any further asylum seekers as a favour to Australia. So what happens now?

Labor's Marles has suggested, rather unhelpfully, that the Australia should offer the PNG government 'more money', or ask it to change the law in order to maintain the detention centre. Marles knows PNG better than most: back in 2013 he was dispatched by Prime Minister Rudd to negotiate the Regional Resettlement Arrangement with PNG's Prime Minister Peter O'Neill. That negotiation resulted in more aid for Papua New Guinea in health, education and law and order in an arrangement known as the 'Joint Understanding'.

Offering more money to the PNG government now would not enable the resettlement of the refugees. Papua New Guinea is in the midst of an economic crisis that is putting extraordinary pressure on its budget. Even if Australia is footing the bill, it will become increasingly difficult for the PNG government to allocate the resources necessary to support some 900 foreign men in a stagnant economy. The government would find it difficult to justify special treatment for the refugees to its people, suffering from the effects of drought, and general elections are only a year away.

At a time when Peter O'Neill stands accused of corruption, suggestions that Australia should offer 'more money' to the PNG government to persuade it to ignore or subvert the Supreme Court's judgment, or to change the nation's laws are highly inappropriate.

Both major parties in Australia need to start being frank with voters about the future of the asylum seekers on Manus. The PNG government will close the detention centre and refuse to resettle refugees. Manus can no longer be the deterrent Australia wants it to be and it will be incumbent on the Australian government to relocate the detainees to another country. A responsible government in Canberra cannot willfully breach PNG's constitution, snub the Supreme Court, or ask the PNG government to prioritise resettling refugees when its budget for essential services is already under huge strain.

Immigration Minister Peter Dutton's claim that the government had anticipated the Supreme Court decision for some months suggests it will have considered what it might do about relocating the detainees. Given previous failures to persuade third countries to take refugees from Manus and Nauru, and Australia's refusal to accept New Zealand's offer to accept some of the refugees, the option Canberra is most likely to be considering would be moving refugees from Manus to Nauru.

Nauru is also in the midst of an election campaign and not without its own problems. The Nauru government's lack of commitment to the rule of law, its lack of transparency, and its antagonism towards journalists have created headlines over the last two years. It has earned the opprobrium of the New Zealand Foreign Minister Murray McCully, who cut off aid to Nauru's justice sector due to concerns about the rule of law. If Nauru is indeed the preferred option to rehouse the Manus refugees, the voters of Australia and Nauru should be informed while they have an opportunity to express a view at the ballot box.

The major parties in Australia should also be canvassing other options. If the Manus 'deterrent' can no longer be a key plank of Australia's immigration policy, how much symbolic value is there in 'never' permitting refugees currently detained in Manus access to Australia or to New Zealand, while we continue to risk our bilateral relationship with Papua New Guinea? Australian voters have accepted policy backflips before and no doubt will again. Our politicians might even persuade us to do so this time if they do us the courtesy of involving us in an informed debate.

Photo Ryan Pierse/Getty Images