Moral responsibility and mental disorder: A philosophical exploration of the insanity defence.

This article examines the insanity defence as a legal and philosophical means of extinguishing moral responsibility due to mental disorder, focusing primarily on its application in England and Wales and comparing it with other jurisdictions. It argues that mental disorder may exculpate a defendant under four conditions: (1) defects of reason, where a person is weakly or non-responsive to reasons to act otherwise; (2) deficits in moral or factual knowledge of wrongfulness; (3) impairment of volition or control, involving a near-total inability to control one's actions; and (4) inability to form the relevant mens rea (criminal intent) due to severe mental disturbance. The article highlights the recent English case of R v Keal, which illustrates conceptual problems with the current defence's lack of a volitional element, and advocates for its inclusion with a high threshold to better align with other jurisdictions and philosophical accounts of moral responsibility. It also discusses how delusions, particularly those involving perceived external control, relate to these criteria and the broader question of whether mental disorder constitutes a form of manipulation affecting responsibility.