A PDF version of this book is available for free in open access via www.oup.com/uk as well as the OAPEN Library platform, www.oapen.org. It has been made available under a Creative Commons Attribution-Non Commercial-No Derivatives 3.0 license and is part of the OAPEN-UK research project. Whether it is a question of the age below which a child cannot be held liable for their actions, or the attribution of responsibility to defendants with mental illnesses, mental incapacity is a central concern for legal actors, policy makers, and legislators when it comes to crime and justice. Understanding mental incapacity in criminal law is notoriously difficult; it involves tracing overlapping and interlocking legal doctrines, current and past practices of evidence and proof, and also medical and social understandings of mental illness and incapacity. With its focus on the complex interaction of legal doctrines and practices relating to mental incapacity and knowledge - both expert and non-expert - of it, this book offers a fresh perspective on this topic. Bringing togetherpreviously disparate discussions on mental incapacity from law, psychology, and philosophy, this book provides a close study of this terrain of criminal law, analysing the development of mental incapacity doctrines through historical cases to the modern era. It maps the shifting boundaries aroundabnormality as constructed in law, arguing that the mental incapacity terrain has a distinct character - 'manifest madness'.