This paper is not so much concerned with the question under which circumstances self-defense is justified, but rather with other normative features of self-defense as well as with the source of the self-defense justification. I will argue that the aggressor’s rights-forfeiture alone – and hence the liberty-right of the defender to defend himself – cannot explain the intuitively obvious fact that a prohibition on self-defense would wrong victims of attack. This can only be explained by conceiving of self-defense also as (...) a claim-right. However, I will also argue that a claim-right cannot ground the self-defense justification either. Rather, what grounds the self-defense justification and its particular strength and scope is the fact that self-defense is an act-specific agent-relative prerogative: a defender is allowed to give particularly grave weight to his interest in engaging in self-defense, which distinguishes self-defense from most other acts. This is not the same as saying that he has a right or a liberty to engage in self-defense. Thus, self-defense, understood as a normative concept, is a claim-right, a liberty-right, and an act-specific agent-relative prerogative. (shrink)