Morally excused but socially excluded: Denying agency through the defense of mental impairment

Abstract

Defendants can deny they have agency, and thus responsibility, for a crime by using a defense of mental impairment. We argue that although this strategy may help defendants evade blame, it may carry longer-term social costs, as lay people's perceptions of a person's agency might determine some of the moral rights they grant them. Three randomized between-group experiments (N = 1601) used online vignettes to examine lay perceptions of a hypothetical defendant using a defense of mental impairment (versus a guilty plea). We find that using a defense of mental impairment significantly reduces responsibility, blame, and punitiveness relative to a guilty plea, and these judgments are mediated by p..