Recent work in the philosophy of criminal law has given renewed prominence to the distinction between offences and defences. Unconvinced that this is merely a technical distinction drawn for the purpose of allocating burdens of proof as between the parties to criminal proceedings, several theorists have attempted to establish that the distinction is rooted in the general theory of responsibility, and that it has significance beyond the criminal law. In this fascinating work, Lu?s Duarte d’Almeida joins those who deny that the distinction is merely a technical one. He also agrees that it has a significance reaching well beyond the criminal law, extending into the whole theory of rules and exceptions in practical reasoning. But he argues that all this is nonetheless compatible with an understanding of the distinction that ties it very closely to the theory of proof. The first moves of Duarte d’Almeida’s book lay the foundation for these claims by retrieving some ideas from H.L.A. Hart’s early (and later disowned) arguments about the role of defences in law and morality. Duarte d’Almeida’s sophisticated reworking of these ideas provides the groundwork for his original account of the more general distinction between rules and exceptions. He shows how this view casts new light on several issues and problems, including the notion of the burden of proof and the distinction between offences and defences in criminal law.