In this monograph Arlie Loughnan examines the criminal law's response to what she terms ‘mental incapacity’. This takes her beyond a study of the ‘defence of insanity’ to consider a wider range of doctrines including infancy and intoxication, infanticide and diminished responsibility. Drawing on historical research and on legal theory, the author challenges various orthodoxies in criminal law scholarship, and reconceptualizes the relationship between the criminal law and forms of mental incapacity. The book casts new light on established topics, and does so at a time when law reform agencies in this country and elsewhere are turning their attentions to this part of the criminal law. This monograph should therefore be an important resource both for legal scholarship and for law reformers.