The idea that judges have a duty to be sincere or candid in their legal opinions has been subject to systematic criticism in recent years. Critics have argued that a strong presumption in favor of candor threatens judicial legitimacy, deters positive strategic action on multi-member courts, reduces the clarity and coherence of doctrine, erodes collegiality, and promotes the proliferation of fractured opinions. Against these and other objections, I defend the view that judges have a duty to give sincere public justifications for their legal decisions. After distinguishing the concepts of sincerity and candor, I argue that the values of legal justification and publicity support a principle of judicial sincerity. This principle imposes weaker constraints than a general duty of judicial candor. But while candor may be desirable, judges who provide sincere justifications for their decisions satisfy the demands of legitimate adjudication.