On Legal Expertise

Abstract Legal experts can reliably ascertain which legal norms are valid, and therefore which legal propositions are true. Legal experts are in this position because they have a grasp of the deep cognitive structure of law: the habits, commitments, and values that characterize the practice of legal argument in a specific jurisdiction. Legal expertise, thus understood, determines the content of the law, which is therefore not reducible to an aggregation of authoritative legal texts. Because social facts about legal experts’ values and commitments can determine the content of the law, references to moral considerations and principles of justice as valid legal reasons, in legal argument, are not a problem for (at least some forms of) legal positivism. Legal expertise thus shows that non-positivists might be right about (as they would put it) the irreducibility of legal content to communicative content without being right about the claims that moral facts determine the content of the law or that the validity of legal norms turns on moral considerations. Legal expertise also plays an important causal role in legal decision-making and is not, as some of the literature on judicial decision-making might suggest, epiphenomenal. From a moral perspective, while the existence of a class of legal experts is not necessarily valuable, it does have certain benefits, particularly in conditions of moral disagreement.