The Dynamics of Legitimacy Change for the US Supreme Court

This study examines how the Court's highly salient decision in NFIB v. Sebelius affected its legitimacy using a nationally representative panel survey that assessed legitimacy perceptions before and after the decision. The study proposes that perceptions of what influences the Court's decision-making process moderate the relationship between legitimacy change and policy output. It describes the multiple modes of evaluation theory that governs this relationship and applies it in the novel context of the policy attitude-legitimacy relationship. The results reveal that when the Court is perceived as using a principled or legalistic decision-making process, legitimacy always increases, irrespective of a person's agreement with the decision. When the Court is perceived as ideological, a pleasing decision increases legitimacy and a displeasing one decreases legitimacy. Finally, when the Court is perceived as affected by public opinion, its legitimacy is unaffected by both pleasing and displeasing decisions.