In a forensic assessment of criminal responsibility in India (under BNS 2023, replacing IPC Section 84), a person is deemed not guilty by reason of unsoundness of mind if at the time of the act they:
- A Had any diagnosed mental illness at the time of the act
- B Could not control their impulses due to a personality disorder
- C Were under the influence of substances prescribed by a doctor
- D Were incapable of knowing the nature of the act, OR did not know it was wrong or contrary to law, due to unsoundness of mind ✓
Explanation
Section 22 of the BNS 2023 (replacing Section 84 IPC) provides the M'Naghten-based test for criminal insanity in India: the accused is excused if, at the time of the act, due to unsoundness of mind, they (1) did not know the nature of the act, OR (2) did not know the act was wrong or contrary to law. The test is purely cognitive — it does not include volitional/irresistible impulse defences. Mere presence of a mental illness is insufficient; the illness must specifically impair the defendant's knowledge of the act at the time it was committed. Personality disorders and voluntary intoxication do not meet this threshold.
Reference: Kaplan & Sadock's Synopsis of Psychiatry, 11th ed.
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Written and medically reviewed by the StethoPrep medical team.