<p>Reasonable mistaken self-defense cases are those in which the defendant who harmed another had a reasonable but false belief that they had to do so in order to prevent that person from inflicting imminent harm on them. The law treats these as justifications rather than excuses. Unreasonable true self-defense cases are those in which the same belief accompanies the defendant’s harmful action, but while true, the belief is unreasonable. The law treats these as excuses rather than justifications. A moral challenge to both legal practices is considered. The legal practices are then defended from the moral challenge by drawing on Stephen Darwall’s concept of a second-personal reason, and on the idea that action that appears aggressive to a reasonable person provides second-personal reason to inflict harm on the apparent aggressor, even if that appearance is deceptive.</p>