You seem to be overlooking the point. Would it be morally permissible for me to scribble down arbitrary rules and enforce them on you if I had an army with which to ensure your compliance?
Laws are just arbitrary rules decided on by a small group of people, much like they were with Kings and their inner circles. Laws are enforced in much the same way too - there's no practical difference between getting assaulted by the King's Guard and getting assaulted by men in blue costumes.
You and what army?
(Not trying to be snarky. That quote seems very apt.)