Insanity as a General Defence in Crimes: M'Naghten Legacy from Section 84, IPC to Section 22, BNS

This article examines the defence of insanity in Indian criminal law, focusing on Section 84 of the Indian Penal Code (IPC) and its counterpart, Section 22 of the Bhartiya Nyaya Sanhita (BNS) 2023. It situates the Indian rule in the context of international doctrines – notably the M'Naghten Rule (cognitive test) and the Durham "product" test and shows that Indian law remains firmly based on the cognitive M'Naghten standard. We analyse key legal principles: the accused carries the burden of proving legal insanity under Section 105 of the Indian Evidence Act, on a preponderance of probabilities, at the time of the offence. Leading cases (Ratan Lal v. State of M.P., Surendra Mishra v. State of Jharkhand, and others) are reviewed. In Surendra Mishra (2011), the Supreme Court stressed the difference between medical and legal insanity, holding that a mental disease per se does not excuse an accused unless it robbed him of the capacity to know the nature or wrongness of his act Procedural provisions (CrPC Section 328–335) for mentally unsound accused such as postponement of trial and the "special verdict" of "guilty but insane" are outlined. The article also discusses empirical trends, contemporary debates, and the impact of the 2023 legal overhaul. It is noted that Section 22 BNS largely mirrors Section 84 IPC. Critics argue this was a missed opportunity to modernise the defence, for example, by explicitly recognising diminished capacity or affective/volitional impairment. The conclusion considers possible reforms to make the law more nuanced and aligned with psychiatric science, while safeguarding fundamental legal principles