Law everywhere is meaningless unless “we have to follow the law” is a cultural norm. This is why norms are more fundamental and more important than laws.

You are discovering this. It wasn't that long ago when the national guard took tuition money away from Kent State in the form of executing their students for free speech.

Federal law is insanely complex. It's written by humans in an abstract legislative process so there's not even a guarantee that it won't conflict with _itself_. We have, several times, added laws to the register that were later determined to be in conflict with the Constitution itself.

This is why courts exist.

This is also why libertarians exist.