Exactly, or at least a single ethical principle. The gist of the argument is that Law must derive from an ethical principle (not a moral one). Here in the U.S. we keep trying to establish ethics through Law (legislation) but that is putting the cart before the horse. The point of origin for Law needs to be an ethical principle or theory and it needs to be established in a manner that cannot be overwritten by legislation, such as being included in a constitution.