I think there is no real existing society which allows ethics-based decisions. The word "should" you use refers to the fact that all the wide-spread ethic positions within a society are reduced to a set of laws and thus are no longer question of gratuitousness but of obedience - moral instead of ethics. To me the whole question is meaningless, as in real existing societies it is a question of power wether you can establish your purposes as societally desired or not. May be that ethical arguments can assist this power but this seems to be secondarily

Roger