Sometimes yes.
> I was under the impression that the principle of supremacy isn't absolute and doesn't extend to overriding a country's fundamental constitutional rights.
What are a country's fundamental constitutional rights can be "dynamically adjusted" depending on the political wishes. :-(
> With authoritarian regimes gaining power everywhere, it would only take a few of them working together to pass an EU law that makes everything fair game.
There is a reason why more and more EU-skeptical movements gain traction in various EU countries.
Specifically for Ireland, we are the only EU member state where the Constitution ordains a referendum to validate ratification of any amendments that result in a transfer of sovereignty to the European Union; such as the Nice Treaty which we can prevent from passing on an EU level. Ratification of other Treaties without the sovereignty component is decided upon by the states' national parliaments in all other member states.
Ireland, Netherlands, and Luxembourg also have veto powers when it comes to EU wide regulations. That's why Article 116 exists.
In the particular, the Seville Declaration recognised the right of Ireland (and all other member states) to decide in accordance with National Constitutions and laws whether and how to participate in any activities under the European Security and Defence Policy.
https://en.wikipedia.org/wiki/Seville_Declarations_on_the_Tr...
It's enshrined in German Case Law as 'Identitätsvorbehalt'.
https://www.bpb.de/kurz-knapp/lexika/das-europalexikon/30945...
The Polish constitutional court has also ruled that EU law does not supercede national law. Thus, primacy of EU law is wholly rejected in Poland.
https://www.euronews.com/2021/10/07/polish-court-rules-some-...
What does "supremacy class" mean?
False.
> The principle was derived from an interpretation of the European Court of Justice, which ruled that European law has priority over any contravening national law, including the constitution of a member state itself.
That is sort of like a supremacy clause, and of course it's valid for the EU.
But that doesn't mean that a Swedish or German etc. court can let that override our basic law. Our basic law is after all the foundation of our law, so if something conflicts with that, it obviously can't be valid.
It is also part of the Treaty of Lisbon via the EU Charter of Fundamental Rights, which is the closest thing to a constitutional level law for the EU.
Not that this has ever stopped anybody.
Because that would technically make any present day wiretap illegal too.
So the detail is written in normal law tract...