What Australia designed on Nauru is a sophisticated work-around: a way to wash its hands of responsibility for these asylum seekers. Today, the High Court backed the Federal Government's cleverness, writes Michael Bradley.

I'll put it as simply as I can: the High Court has placed its seal of approval on a piece of legal sophistry which is, when you boil it down, just a cheap con.

It's tragic that the regional processing arrangements between us and Nauru have been upheld; it's sad in the human sense that this appalling travesty is going to continue unabated and that over 250 traumatised people, including dozens of children, now face imminent deportation back to Nauru.

But it's tragic for the law too. I'm ashamed to say that our Highest Court has been done over by experts.

There is one sliver of light on this tough day - the lone dissenting voice of Justice Michelle Gordon, the most junior member of the High Court bench. She has delivered a stingingly clear opinion which clinically cuts through the arguments of the Commonwealth and shreds them, exposing the really ugly truth which the whole Court should have seen.

The plaintiff in this case was a Bangladeshi woman who was on a boat intercepted at sea, detained and then forcibly removed to Nauru in January 2014. She was held in detention at the Regional Processing Centre (RPC) there until August 2014, when she was flown back to Australia for medical treatment. The case was about whether she (and her baby, born here) can be lawfully returned to Nauru.

The legal arguments were, as you'd expect, complex. They required detailed interpretation of the Australian Constitution and the Migration Act. But it boils down to this: who is detaining the asylum seekers on Nauru; and, to the extent that Australia is involved in that, is it legal?

The majority determined that the detention is being carried out by the Government of Nauru. Yes, the Australian Government effectively brought that detention about, by providing and paying for all of the material support necessary for the establishment and maintenance of the RPC, applying for the necessary visas and paying the visa fees. But to that extent, that was within the legal power of the Commonwealth under our Constitution, and therefore entirely valid.

Gordon J said that reasoning is plain wrong. She found that it is Australia who detained the plaintiff on Nauru, and she identified 12 specific actions of the Commonwealth Government which make this conclusion unarguable.

I think these actions are worth reciting:

1. designating Nauru as a "regional processing country" to which certain "unauthorised maritime arrivals" must be taken; 2. signing a Memorandum of Understanding with Nauru, under which Australia could decide to send asylum seekers to Nauru and Nauru must accept them, with all administrative arrangements and costs to be undertaken by Australia; 3. physically removing the plaintiff to Nauru; 4. applying to Nauru for a protection visa on the plaintiff's behalf, without her consent, and paying the $3,000 visa fee, knowing that the visa conditions included forcible detention in the RPC; 5. via its contractors (Transfield and Wilson Security), taking the plaintiff to the RPC and, by Commonwealth officials, providing all her documentation to the RPC; 6. contracting with and paying Transfield to run the RPC; 7. providing the perimeter fencing, gates and towers at the RPC; 8. contracting with and paying Transfield to provide the security services in the RPC under rules stipulated by Australia; 9. requiring and authorising Transfield to "exercise use of force" on the plaintiff in certain circumstances; 10. having deep ongoing involvement in the day to day running of the RPC, including appointing the Operational Manager running the RPC and having a Border Force team present in the RPC at all times; 11. retaining the power to "step in" to Transfield's contract, so that the Border Force itself could go into the RPC and directly enforce all the detention powers it had given to Transfield; 12. controlling the content of the Offshore Processing Guidelines, which governed how Transfield had to run the RPC.

I would add this extra piece of bureaucratic cynicism: each protection visa expires after three months.

As Gordon J found:

It has been the general practice of the Nauruan Justice Secretary to grant a further RPC Visa to the Transferee without requiring a further application by a Commonwealth officer ... and without seeking the consent of that Transferee. It has been the invariable practice on Nauru for the form of the RPC Visa issued in respect of Transferees to specify the Nauru RPC as the place at which the Transferees must reside. The Commonwealth has paid all RPC Visa fees payable, which, as at 30 March 2015, totalled $27,893,633.

The rest of the legal argument is about whether this detention of asylum seekers is punitive in nature. If it is, it can't be lawful. On this point, the majority makes its laziest logical leap. Having acknowledged that the MOU between Australia and Nauru expressly states that its central purpose is to deter people from trying to get to Australia by boat, the judges simply conclude that that fact alone doesn't mean that the detention of asylum seekers on Nauru under the MOU is designed to punish them.

But, of course, we all know the reality of this, even if we pretend otherwise. These people are sent to Nauru, detained there indefinitely, and treated appallingly, precisely so that everyone will know that the result of getting on a boat is that you'll end up in a tropical hell hole. The whole idea is to use them and their plight as a salutary example. If that isn't punitive, I honestly don't know what is.

Let's just stand back from the legal niceties for a moment here. What Australia designed on Nauru is a sophisticated work-around. The end purpose is to stop the boats. To get to that end, the Government had to find a way to abdicate its legal responsibilities under the Refugee Convention and wash its hands of the asylum seekers who are within its care. It sought to achieve that by a legal fiction: we send them to Nauru, Nauru agrees to take them, and, from then on, they are Nauru's problem.

From then on, they are outside the protection of our legal system; they are, for Australian legal purposes, non-people. Their fate rests with the government of a nation with a population of 10,000 and no functional economy.

To make the whole set-up work practically, Australia provides everything and pays for everything. It just takes no responsibility for what happens to the people caught up in this Machiavellian mess. I don't need to mention the rapes, assaults and other horrors to make my point but, for pity's sake, what are we doing?

The High Court has used its black letter legal expertise to dispassionately pick through all the contracts and laws to effectively congratulate the Australian Government on its cleverness. Gordon J, by contrast, has seen right through it. Sadly, there's only one of her.

Of all the dark, awful days we've had in this shameful episode of Australian history, today is one of the blackest. I'm saddened to say that, today, the law has been an ass.

Michael Bradley is the managing partner of Sydney law firm Marque Lawyers, and he writes a weekly column for The Drum. He tweets at @marquelawyers.