 These considerations should settle matters but do not do so for those who maintain that killing, in medical contexts, is always morally unjustified – a premise that underwrites much of the debate surrounding this fourth objection. But this underlying assumption is open to challenge and has been challenged by, for instance, Rachels 1986 and McMahan 2002. One of the reasons the challengers have given is that there are cases in which killing a competent dying person when she requests assistance with dying, is morally preferable to allowing her to die, namely, when taking the latter option would serve only to prolong her suffering against her wishes. Further, despite the longstanding legal doctrine that no one can justifiably consent to be killed (on which more later), it surely is relevant to the justification of an act of killing that the person killed has autonomously decided that she would be better off dead and so asks to be helped to die.