Then you do not know our history. Look up the origin of Lex Rex - do a google search. It came from Samuel Rutherford. The reason we have a Constitution is to prevent MEN from governing by FIAT or whim. It is the law of the land and no man can change it. The people can change it ONLY by amendment. Law is king. Get it?
I do tend to believe TheAngryClams theory regarding Roman influence though.
You can sincerely believe whatever you want, but you would be sincerely wrong in this case.