Look at the real world. Do you really need me to give you a lesson on constitutions? Judges shoot down laws that are unconstitutional. Judiciary over rules the government.
You are the one introducing the concept of a global constitutional government. Do you know what you mean by that or not?
Yes... I've been jumping back and forth between national and global discussions. That said it would be the same as in all western nations. A court would overturn unconstitutional laws.