Earlier quoted context omitted.
> no longer countries Well, no. The entities united in the European Union are still Countries - Sovereign States, "governments over permanent populations in defined territories enabled to relate with peers, entering as part of the international community after recognition from at least one peer". They have embassies and deal with embassies. The distinction you are trying to convey, allegedly changing the scenario in…
EU law arguably has a greater weight than individual constitutions now. There are some countries like Poland which claim to not accept that, but the principle of EU law supremacy has become generally accepted (even without a referendum in that sense...)
One situation where this almost happened was during the discussion on Eurobonds. [0]
[0] https://www.dw.com/en/eu-launches-infringement-proceedings-a...