AbstractIn his bookHard Cases in Wicked Legal SystemsDavid Dyzenhaus aims to provide a cogent refutation of legal positivism, and thus to settle a very old dispute in jurisprudence. His claim is that the consequences for practice and for morality if judges adopt positivist ideas in a wicked legal system are unacceptable. He discusses the South African legal system as a case in point. I argue that this claim is not secured. Dyzenhaus has three arguments for his view. The first is that positivism cannot account for legal principles, and legal principles are the key source of morally acceptable adjudication. I show that his argument does not go through for sophisticated positivist accounts of “principles” such as those of J. Raz and D. N. MacCormick. Dyzenhaus's second argument claims to find a pragmatic contradiction in positivism, between the belief in judicial discretion and the belief in a commitment to legislative sources as binding fact. I argue that there is no such commitment in a form that supports Dyzenhaus's theory. His final argument is that wicked legal systems are contrary to the very idea of law and legality. I argue that a strong doctrine of deference to legislative authority cannot be bad in itself: It can only be bad relative to a certain content to legislation. Thus Dyzenhaus's claim begs the question against positiv