At the height of the financial crisis, we changed our tax laws to provide for a domicile levy on certain Irish citizens whose worldwide income exceeded €1 million, whose property in Ireland was greater in value than €5 million, and whose liability to Irish income tax in a relevant tax year was less then €200,000. In 2012, the domicile levy was amended to apply to non-citizens as well.

This meant such wealthy tax exiles would pay at least €200,000 to the Irish state, but any Irish income tax which they paid could be offset against the €200,000 levy. The idea was to introduce a smidgen of social justice on paper, but the result has been very disappointing. Only ten or 12 people now pay the levy each year. It only brings in around €2.5 million, at best.

While many ordinary mortals (with some exceptions for foreign-based executives) are paying more than half their marginal earnings in tax, PRSI and USC, some of our wealthiest citizens choose to live in tax havens where they are subject to little income tax.

They are allowed to visit Ireland for up to 140 days each year, to buy and own magnificent trophy homes in Ireland, to take shareholdings in Irish businesses, including our media and, unless they can legally avoid the domicile levy of €200,000, give very little of their worldwide income to the Irish exchequer by way of income tax.

We are not told (presumably for confidentiality reasons) who pays the domicile levy each year, but we can count them on the fingers of two hands. You might think that our republic has been very kind to plutocrats, and you might think that they should be very grateful that they get off so lightly. They can be here for 20 out of the 52 weeks in any year. They can spend the rest of their time in other trophy homes in exotic places, and they can avoid having their marginal earnings taxed here at 50 per cent, all at the same time.

The €5 million Irish property threshold does not include shares in a company which exists wholly or mainly for the purpose of carrying on a trade or business, or shares deriving their value from property located in the state.

When Phil Hogan in 2011 appointed a Forum on Philanthropy, its then chairman Frank Flannery proposed an additional 43 days entitlement to reside in Ireland (that is, 183 days or more than half of the calendar year), in exchange for philanthropic investments (at least €15 million) in Ireland.

This was intended to incentivise our tax exiles into further acts of domestic philanthropy. If Flannery’s proposal had been accepted, such tax exiles would have been further rewarded by a licence to spend more than half their lives in Ireland.

As someone who opposed and ultimately abolished Ireland’s ‘citizenship for sale’ scheme when minister for justice, the idea of tax residency for sale seems to me to be equally unacceptable.

As journalist Harry McGee reported, the Flannery proposal ran into stiff resistance from other members of the voluntary forum, so Flannery informed a meeting of the forum in September 2013 that he would be “mindful of the concerns expressed”.

But at the next meeting of the forum in November 2013, Flannery insisted a large source of funding would be available under his proposal and that he would continue to promote it, but only on a “personal basis”. We still don’t know who the scheme’s backers were.

In July 2013, Michael Noonan had apparently written to an Oireachtas committee describing the proposal from Flannery as “attractive”. The secretary general of the Department of Finance, John Moran, had expressed misgivings about the idea. The Oireachtas committee expressed its own doubts about the proposal and, ultimately, it was not included in the Fine Gael/Labour government’s next Finance Bill.

All of this came to mind when I read that JP McManus, one of our better known tax exiles, had won a vast amount, reputed to be over $17 million, in a backgammon match in the US with fellow multimillionaire Alec Gores, a US businessman reputed, like McManus, to be worth billions.

The Irish Independent reported on May 1, 2016 that the backgammon session lasted three days, and that Gores had “paid up like a gent”. But it also reported Gores had withheld a portion of JP McManus’s winnings and had handed it over to the US treasury to “cover any potential US federal tax liability”.

JP McManus then sought repayment of the $5.2 million withholding tax in the US Court of Federal Claims in proceedings heard before Judge Nancy B Firestone. He lost his claim last week.

While the reasons are not yet public (Judge Firestone sealed her judgment temporarily), it is clear from court documents that JP based his legal claim for the $5.2 million in part on the argument that he was considered subject to taxation in Ireland for the purposes of the US/Ireland double taxation agreement because he had paid us the €200,000 domicile levy.

The US government argued that for McManus’s claim to succeed, he had to show he was subject to “comprehensive tax liability” in Ireland and that the €200,000 domicile levy did not amount to “comprehensive tax liability” in respect of his worldwide earnings. McManus may yet appeal the decision.

He is widely credited with great acts of philanthropic generosity to many causes in this state. I, for one, do not envy him his wealth or his success. If I had achieved either his success or his wealth, I too might be tempted to avail of our generous tax laws to join the small group of extremely wealthy people who have chosen to become non-resident to avoid income tax laws which govern the rest of us in this republic.

It is only when you see the hard cases of Irish citizens denied life-changing medical treatments because of cost that you get a true perspective on the generous tax treatments we give to some of our wealthiest citizens.

That $17.2 million could be won and lost on the backgammon board by player skill and dice rolls demonstrates the difference between the very, very lucky and the very, very unlucky in our republic.

In the Celtic Tiger years, Mary Harney and I argued strongly at cabinet that all wealthy Irish citizens should be liable for a minimum tax liability regardless of residence.

The Constitution says that “fidelity to the nation and loyalty to the state are fundamental political duties of all citizens” and that “all citizens shall, as human persons, be held equal before the law”. As George Orwell’s porcine revolutionaries put it, “some are more equal than others”.