A law is successful primarily because the behavior it prescribes has attained the status of custom. Just as manners are observed not because of sanctions attached to them but because, through repetition, contrary behavior becomes unthinkable, so societal laws are obeyed not because the behavior is ethically required or because penalties await those who act otherwise, but because to act otherwise would be uncustomary.
 As with manners and other customs, laws vary from society to society is utilized by the argument.