Recent literature on the relationship between knowledge and justice has tended to focus exclusively on the social and ethical dimensions of this relationship (e.g. social injustices related to knowledge and power, etc.). For the purposes of this article, I am interested in examining the virtue of justice and its effects on the cognitive faculties of its possessor (and, correspondingly, the effects of the vice of injustice). Drawing upon Thomas Aquinas’s account of the virtue of justice, I argue that in certain (...) cases justice can be a criterion of epistemic evaluation and that it deserves more attention than it has been given among virtue epistemologists. More precisely, the virtue of justice may become a criterion of epistemic evaluation in cases when a belief is formed on the basis of testimony. It would seem that there are cases when A’s assent to proposition p is something that is owed to B on the basis of B’s testimony; or there may be instances when A is culpable for declining to let B’s testimony have any effect on A’s belief. I briefly sketch four distinct scenarios in which this bears out. (shrink)