The argument from marginal cases (also known as the argument from species overlap) is a philosophical argument within animal rights theory regarding the moral status of non-human animals. Its proponents hold that if human infants, senile people, the comatose, and cognitively disabled people have direct moral status, non-human animals must have a similar status, since there is no known morally relevant characteristic that those marginal-case humans have that animals lack. "Moral status" may refer to a right not to be killed or made to suffer, or to a general moral requirement to be treated in a certain way.