This isn't the theory people used before WW1. This is exactly why the EU is not just an economic union, it's a political and judicial one as well. No on before

This isn't the theory people used before WW1. This is exactly why the EU is not just an economic union, it's a political and judicial one as well. No on before WW1 would have even considered the idea that a French judge in a common European court could tell the German government what they can or can't do with respect to their own internal laws. Today, this is routine.