So, that old US corporate taxation friend, the inversion, is gone.

That’s the trick that enabled companies from far away acquire companies in Ireland, and run their taxes – “invert” them – through Ireland’s corporate tax rate of 12.5 per cent, which is much lower than US tax rate of 35 per cent.

The most recent and very high-profile example of a (planned) inversion was the proposed $160 billion takeover of Irish company Allergan by the much larger pharma giant Pfizer. Taxes would have been processed through Allergan in Ireland, though the gains to the Irish exchequer would have been very limited.

Then last week, the Obama administration swiftly brought in new US Treasury Department taxation rules that blocked such beneficial inversions, which President Obama called "one of the most insidious loopholes out there".

In under 48 hours, the new rules torpedoed the Pfizer deal.

Politicians and various pundits in the US have been droning on about such tax dodges for ages. Years, actually. The favoured posture to adopt on tax inversions from the bully pulpit has been to complain that Ireland – or some other lower cost country – facilitates such shenanigans by having such-and-such tax rates or laws, and should therefore, change their tax systems.

The problem is always the laws in other countries.

Obama’s move confirmed just how hollow the grandstanding has been of those who have taken such a stance. People who routinely expressed moral outrage, then picked on the little guy to divert attention, rather than risk offending, say, a large corporate donor base.

Such hypocrisy.

I’ve been saying this for years: the most effective and the most appropriate way to prevent inversions or other tax concerns involving US multinationals is simply, for the US to change US tax rules.

This isn’t to say other countries, including Ireland, shouldn’t take a hard look at their tax systems. Because, yes – of course there’s a global problem with complex dodges, as the recent leak of the Panama Papers makes amply clear.

And yes, those dodges occur even when this wasn’t the intention of the laws brought in here, or in other places. But it’s no surprise that the big multinationals have the wherewithal to hire the legal and financial experts that enable them to exploit both the intended and unintended consequences of corporate and tax law abroad.

Exploitative multinationals

But the home country for those exploitative multinationals – who consistently have noted that they pay their taxes legally as required – is the most powerful gatekeeper in this game.

If the companies are prevented from bringing home the cash generated by using complicated structures abroad, then the vast majority won’t use them.

The death of the Pfizer-Allergan deal showed just how quickly an effective tax change works.

More needs to be done, though. Other changes to US law have been suggested by experts, though the concern is that, if they must be brought in as formal changes to the overall tax system, then years will pass while preparing new legislation.

One easy and quick fix, though, would be for the US to stop declaring regular tax amnesties, where multinationals with assets abroad are allowed to repatriate them at a “once-off” reduced tax rate.

These happen, I am told by people wise in the ways of both law and finance, more or less about every decade.

Multinationals have many complex ways of moving offshore cash and assets around, and these can and should also be far more transparent (as is in part, the goal of new legislation proposed by the EU this week).

But the big event remains those ritual tax amnesties that have been supported by so many successive administrations in the US, but remain unremarked upon by the politicians eager to complain about everyone else’s defective and exploitable tax laws.

To be fair, perhaps many don’t even know they happen. The amnesties don’t tend to generate much political or press interest, maybe because they aren’t as fiendishly dramatic as tax inversions, the “double Irish”, or the “Dutch sandwich”.

But they are reliable, slightly-ajar doors that multinationals know will eventually be fully opened for just long enough to allow them to bring back cash at a good discount to the usual US tax rate.

Then the game, and the stockpiling of cash, begins all over again. Until the next amnesty.

Halting those amnesties would halt many of the other questionable tax schemes too, because the cash saved through using them would be stuck offshore.

When such amnesties are made impossible in US tax law, then we’ll know the big picture issue of tax dodging has at last been taken seriously.

But this will be far more politically challenging, than sniping at tax law in smaller nations abroad. So don’t get your hopes up.