If there is no treaty validating ECJ Supremacy, then that's it. Even a 'statement' or 'interpretation' by an Judge or Expert will be called into question.
Also - you may despair in the short run for the authoritative nature of 'Hungary' but there is a much bigger issue and that is the consolidation of power at the EU level.
Hungary has elections for it's leaders.
The EU does not.
You did not vote for Ursula Von Der Leyen. She was not a candidate, and was totally unknown outside Germany before the election. She was not vetted. She had little public history. Voters did not select her.
She was chosen in a backroom deal: "Here is your new President. We selected her for you. You will find about her platform, later, we hope you like it because obviously you didn't vote for it". Ursula von der Layen layed out her vision for EU long after voters even knew who she was.
The EU Treaties only in 2007 even require the selection of the Pres. to even barely take into consideration the 'recommendation' of MEPs, even then, they have no power. MEPs cannot introduce legislation or sanction leaders.
The EU is the least democratic 'layer' of European governance, combined with the fact that it is at the 'top' and sometimes has the most authority, is a pretty scary thing in terms of the balance of power.
So the EU is 'good for dealing with PiS' yes, probably. But there are other, broader issue.
In Russia people vote for the president, but that does not matter much - what matters is who owns the press and counts the votes. Which is exactly what PiS and Fidesz did: they owned the press. And PiS also messed withe the judges and quite openly admitted to having bough spyware which was used to spy on the opposition. That's the difference between the EU, Poland and Hungary.
> wouldn't it be extremely prudent to parameterize what exactly those authorities are?
TFEU
The ECJ decisions are actually more like recommendations on how the local courts should act.
Countries that don't follow the rulings can't complain if they're suspended from EU resources and mechanisms while that is not solved, like having their exports blocked, be removed from Schengen, etc. (And if they don't like it they're free to complain to the walls since they don't recognize the ECJ...)
ECJ rulings are the law of the land as far as they see it, not a 'recommendation'.
There are no rules around sanctions etc. for countries that don't 'comply'.
It's just 'make it up as they go along'.
The problem is: there is no treaty basis for ECJ Supremacy. By opening that can of worms, the EU may find themselves with a 'big losing hand' and more affirmatively lose their power.
As I pointed out in the previous comments, the issue is unsettled even in Germany.
If a bunch of nations are going to get into a kind of Federal Union, and have a 'court' of some kind, wouldn't it be extremely prudent to parameterize what exactly those authorities are?
If you were the PM/Pres or Supreme Court Judge of any country, wouldn't you think it would be the most obvious and important thing to make it very clear and spelled out in law and treaty?
If the framers of the EU actually wanted to hand over 'Judicial Supremacy' to the ECJ, would they, you know actually write that down?
And absence of it being clear, why on god's green earth would nations hand over a fundamental right, one of the pillars of Liberal Democracy, over to a different institution.
Any and all 'decisions' made otherwise, are hugely indirect and speculative i.e. "Well, we signed treaties with the EU after the ECJ declared Supremacy, therefore, they have Supremacy' is still very indirect.
It's one of the more mind-boggling aspects of EU governance, and if you start to take a slightly cynical look at it, it doesn't look good.
The most pragmatic reason for why the ECJ was never explicitly given power was because: it would be illegal, it would cause major uproar in nation states, it would never pass. So what they did was 'allowed' the ECJ to make a little ruling claiming authority, and then as generations go by, as local courts pile on the deferring agreements, it just 'becomes a reality'.
That's a big speculation of course, but there's just no logic at all for nations handing over Judicial authority without it being fairly clear.
If they were 'nitpicking' at 'some narrow issue' - then fine. There is always ambiguity. But this is not that, it's more fundamental.
It's truly bizarre.
And FYI this is not a resolved issue (See Germany: [1]) and there's still a lot going on.
Also worth a glance [2]
In terms of PiS shenanigans, nuance does matter, I don't think we can just be populist and say 'oh they rejected ECJ Supremacy which is ridiculous and evil' kind of thing. All of these issues are a bit tricky.
I think a lot of people in Europe just think that the ECJ naturally has Supremacy, just like a regular Supreme Court, because that's what was agreed to and Poland is 'off their rocker' - like a US State ignoring a US Supreme Curt ruling. It's not the case though. People would be very surprised at the odd reality.
[1] https://www.politico.eu/article/commission-sues-germany-esca...
[2] https://www.chathamhouse.org/2021/10/law-tool-eu-integration...