Coercive rules and their implementation are,in liberal democratic societies at least, subject to ethical constraints. The state's moral authority requires these constraints to be both cogent and effectively realised in doctrine. In short, the enterprise of subjecting individuals to coercive rules must be consistent with the delivery of criminal justice. Contemporary criminal theory is much exercised by the apparent contradictions and ambiguities characterising criminal law doctrine. Is this an inevitable part of the territory leading us to question the very possibility of criminal law delivering justice? Or, as the author prefers, is criminal justice an achievement in which one of the tasks of criminal theory is to set goals and identify deficiencies in a constant effort to improve the form and content of rules and procedures? Informed by this premise the book explores some of the key questions in criminal theory, addressing first the ethics of criminalisation and punishment. It continues with an examination of the structure of criminal liability with its emphasis on separating consideration of the objective conditions of wrongdoing from the features which make a person responsible for it. Finally it examines attempts and accessoryship with a view to exploring the doctrinal tensions which may arise when competing justifications for criminalisation and punishment collide. The book gives an account of the present state of criminal theory in an accessible style which will welcomed by those embarking upon courses in advanced criminal law and criminal theory, teachers, and more generally by practitioners and scholars.