Dissociative Identity Disorder and the Law: A Comparative Analysis of Criminal Responsibility in England and Vietnam

Dissociative Identity Disorder presents unique challenges to criminal justice systems, particularly in cases where fragmented identity impairs cognitive awareness or volitional control. This article explores how two contrasting legal systems one common law, one civil law approach the issue of criminal responsibility in defendants diagnosed with DID. Employing a mixed-method strategy that combines doctrinal and comparative legal analysis with an empirical survey of 372 individuals using the Dissociative Experiences Scale (DES-II), the study highlights the limitations of binary models of capacity and the under-recognition of partial mental impairment. It argues for a functional, capacity-based framework that assesses the cognitive and volitional state of the operative identity at the time of the offence. The article recommends legal reforms to incorporate intermediate responsibility categories, enhance forensic standards, and permit adversarial testing of psychiatric evidence. These findings contribute to the evolving discourse on mental health and criminal culpability, offering comparative insights for more proportionate and scientifically informed adjudication