The justification of homicide in self-defence requires that self-preferential killing be justified. I argued in 4.3 that lack of intention to kill (where plausibly invoked), together with the requirements of necessary and proportionate force, are insufficient to justify preserving my life by an act which foreseeably kills another person. The conditions of necessary and proportionate force – and, according to some, lack of intention to kill – are moral limits of the right of self-defence: they cannot ground a positive right of self-defence. This is because, as John Finnis stresses, the use of force in self-defence involves an act which would normally be a grave injustice to its victim. In my view, unjust harm is inflicted when an unoffending person is justifiably foreseeably killed as the lesser evil, e.g. where an innocent bystander is killed in the course of defending a group of people, or in the case of necessity where a driver of a runaway vehicle steers into one person rather than several. Even when such foreseen killing complies with the conditions of the Principle of Double Effect, it nonetheless wrongs its unoffending victim in infringing his or her right to life. Unlike justified killing in the course of self-defence or in circumstances of necessity, the use of necessary and proportionate force against an unjust threat in self-defence does not violate its victim's right to life. Because this is so, the justification of self-preference in the case of homicide in self-defence distinguishes self-defence as an exception to, rather than a justified infringement of, the prohibition of homicide.