You might find it difficult, not to mention dangerous, to get to see a real meeting between an irresistible force and an immovable object. But if you’re looking for the next best experience over Christmas, you could well take a look at the ballooning legal spat between Poland and the EU.

To remind you of the background, it is part of Brussels’s catechism that its law must at all times and in all places trump the law of a member State. True, the principle doesn’t appear in the treaties; but the Court of Justice, from which there is no appeal, has said so since 1963. And the rule is unyielding: were the most basic and entrenched constitutional norm to clash with a Euro-regulation on the packaging of bananas, the flick of the Eurocrat’s pen would still take precedence.

Last October, the Polish government asked its own Constitutional Tribunal what it would do faced with a conflict between Euro-law and the Polish constitution. No particular issue was mentioned in the request, which was deliberately framed as something more like an intellectual question or student essay. But the answer was unequivocal: whatever Brussels thought, in Warsaw  the Constitution had to win out.

The EU’s response, announced yesterday, was equally forthright. It has engaged a mechanism for the Court of Justice to tell Poland that this decision is illegal under European law. It wants the court to order Poland to put things right, and if it does not to fine its government heavily for disobedience.

Who is right on the intellectual question isn’t clear. The EU line is that Poland signed up to the EU knowing all about the rule that EU law was sacrosanct. But the Poles can equally plausibly retort that their constitution of 1997 came before their EU membership in 2002, and did not empower any government to sign away to an outside body the right casually to override or amend it. But it doesn’t really matter. This is increasingly a matter not of law but of of raw politics. And here you may well think that the EU is not scoring well.

To begin with, a mere abstract statement of law by a constitutional court is arguably no big deal. The EU has already sought to punish Poland for concrete instances of particular EU laws being broken; politically it would have been far better to limit its complaints to these. To demand that a country’s taxpayers be mulcted in large sums for a mere theoretical pronouncement by its constitutional court looks like cracking a nut not so much with a sledgehammer as with a piledriver.

More interestingly, however, just what is Poland to be asked to do? Presumably either to get its constitutional court to change its mind, or to change its constitution to prevent this ever happening again. But both of these raise big problems.

Is Brussels really asking Poland to lean on its constitutional court to get rid of a results the EU doesn’t like? If it is this, is an extremely unattractive posture, particularly from a body like the EU which sets great store by its attachment to the rule of law.

What then about a constitutional change? As you might expect, this is a serious matter in Poland. Any constitutional amendment needs a super-majority in the lower house and an absolute majority in the Senate, and in certain cases a referendum. There is no way the Polish executive can force the issue. The EU knows this perfectly well. Brussels’s implicit demand is therefore that the Polish people be threatened with substantial fines unless they and their elected deputies reach the right result in a constitutional amendment process. The EU has a long and inglorious history of leaning on governments to run and re-run constitutional votes until they reach the right results (think for example the referendums in Denmark over the Maastricht Treaty in 1993, or Ireland on the Lisbon Treaty in 2009). But threatening to impose legal penalties on those governments for getting things wrong is a new and worrying development.

Of course the EU doesn’t think this way. It sees itself as simply ensuring that the rule of law applies throughout Europe, and taking steps to deal with governments that threaten it. Up till now, moreover, these efforts, even if seen by Eurosceptics as overbearing and intrusive, have nevertheless had some plausibility. In the case of Poland, for example, it is only fair to point out that there are serious allegations of political skulduggery and legal corner-cutting by the ruling PiS party over matters of concern to the EU, for example over the process of judicial appointments, on which there is ongoing argument as to how far this is the EU’s business.

But however murky the legal background, Brussels needs to tread carefully. In particular, its demand that an inconvenient constitutional decision be somehow sidelined or got rid of on pain of pecuniary punishment risks yielding any moral high ground it may once have occupied. The European Commission may see itself as a white knight riding to the rescue of a beleaguered Polish people under the heel of an illiberal government. But it can’t complain if many of those people see instead, three days before Christmas, a rather unseasonal demand from an unelected body for “your money or your constitution.” Hitherto the people of Poland have loyally supported the principle of EU membership. How far they continue to do this is, however, now very much in the EU’s hands.