This paper deals with the conditions of liability to self-defense. When I use the term liability, I mean moral liability. This is different from desert. If I am liable to be killed in self-defense, it does not follow that I deserve to be killed (say, as a means of punishment). In short, desert entails liability but liability does not entail desert. My use of the term in this paper may be stated succinctly as follows: if killing a person will neither wrong him nor violate his rights, he is morally liable to be killed. A person poses an unjust threat when he threatens harms that are neither justified nor excused. A person is culpable for an unjust threat if he intends the threat he poses, is a morally responsible agent, and there are no mitigating circumstances, such as duress, that excuse his actions. A person is at fault, but not culpable, for an unjust threat if he is a morally responsible agent, has acted unreflectively, recklessly, though not maliciously, in a way that poses risks to others. Though culpability entails fault, fault does not entail culpability; as I will explain later, a person does not have to be culpable in order to be at fault for an unjust threat.
Betz '06, Adam, "The Role of Fault in Defensive Killing" (2006). Honors Projects. Paper 11.