This view is not accurate. There is at least the European Court of Justice[1], and there are directives[2], which are laws written and enacted by the European Union, without any national act being necessary. Of course, the Court of Justice (sadly) doesn't have a European Constitution to rule on, but it does overturn national laws sometimes.

[1]: https://en.wikipedia.org/wiki/European_Court_of_Justice [2]: https://en.wikipedia.org/wiki/Regulation_(European_Union)