Bit trickier in the EU. The countries themselves have constitutions that can be amended, with varying ways in which they can be enforced.
In theory this should give sufficient protection, but it becomes a bit complicated if the EU enacts regulations that contradict national laws or even the constitution.
The EU derives its power not from a constitution but from its founding treaties. As best I can tell the EU claims these treaties have precedence, but honestly it's a bit unclear how it could overrule the constitutions that gave the signatories the power to ratify the treaties. I do know that the EU wasn't happy when Poland ruled some parts of these treaties unconstitutional (which is really part of a much bigger political fight, but is illustrative).
Most postwar constitutions explicitly allow for transfer of sovereignty to structures necessary to maintain peace among nations. They were originally meant for UN-like organisms and apply equally to the EU.
Canada’s “constitution” explicitly creates a back door right in section 1. I’ve heard Canadian legal scholars comment that the only part of the Charter that would likely completely stand up against a section 1 challenge is section 12: “the right not to be subjected to any cruel and unusual treatment or punishment”
In theory this should give sufficient protection, but it becomes a bit complicated if the EU enacts regulations that contradict national laws or even the constitution.
The EU derives its power not from a constitution but from its founding treaties. As best I can tell the EU claims these treaties have precedence, but honestly it's a bit unclear how it could overrule the constitutions that gave the signatories the power to ratify the treaties. I do know that the EU wasn't happy when Poland ruled some parts of these treaties unconstitutional (which is really part of a much bigger political fight, but is illustrative).