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Indian criminal law | General exceptions

Section 84 IPC and Section 22 BNS: Act of a Person of Unsound Mind

Section 84 of the Indian Penal Code, 1860, established a defence where a person was legally incapable of understanding the nature or wrongfulness of an act because of unsoundness of mind. The corresponding provision in the Bharatiya Nyaya Sanhita, 2023, is Section 22.

Current law: The Bharatiya Nyaya Sanhita, 2023, came into force on 1 July 2024. Section 22 now provides the corresponding general exception. Section 84 IPC remains relevant to offences committed before the change, subject to applicable repeal, saving and transitional provisions.
Contents

Section 84 IPC: Act of a Person of Unsound Mind

The provision in the Indian Penal Code, 1860, stated:

Nothing is an offence which is done by a person who, at the time of doing it, by reason of unsoundness of mind, is incapable of knowing the nature of the act, or that he is doing what is either wrong or contrary to law.

Section 22 BNS: Corresponding Provision

Section 22 of the Bharatiya Nyaya Sanhita, 2023, preserves the same substantive test. It provides an exception from criminal responsibility when unsoundness of mind, at the time of the act, made the person incapable of knowing the nature of the act or that the act was wrong or contrary to law.

This is a legal incapacity test, not a general exemption for everyone diagnosed with a psychiatric condition.

Essential Requirements of the Defence

  • Relevant time: The incapacity must exist when the act was committed. A diagnosis before or after the event may be relevant evidence but is not decisive by itself.
  • Unsoundness of mind: The inability must arise by reason of unsoundness of mind.
  • Nature of the act: The person must have been incapable of knowing the nature of the act; alternatively,
  • Wrongfulness or illegality: The person must have been incapable of knowing that the act was wrong or contrary to law.

Medical illness and legal unsoundness

Medical evidence can help establish a person's mental condition, but the legal question is narrower: whether the statutory incapacity existed at the precise time of the alleged offence. A medical diagnosis alone does not automatically establish the defence.

Illustrative example

Suppose an accused person experiences a severe mental disturbance and, because of that condition at the relevant moment, cannot understand the nature of the act being performed. If the statutory requirements are established on the evidence, the general exception may apply. The result depends on the facts and the court's findings, not merely on the label attached to the condition.

Burden of Proof and Relevant Evidence

Section 108 of the Bharatiya Sakshya Adhiniyam, 2023 places the burden of establishing circumstances bringing the accused within a general exception on the accused, while the court presumes the absence of such circumstances. The corresponding earlier provision was Section 105 of the Indian Evidence Act, 1872.

The prosecution still bears the burden of proving the ingredients of the charged offence beyond reasonable doubt. Evidence relied on for the exception may also be relevant in assessing whether the prosecution has established the required mental element.

Depending on the facts, relevant materials may include contemporaneous treatment records, psychiatric assessments, reliable witness testimony, conduct before and after the incident, and other circumstances indicating the accused's mental state at the time.

Procedure Where an Accused Cannot Conduct a Defence

A separate question arises when an accused person is currently unable to understand or participate in criminal proceedings. Sections 367 and 368 of the Bharatiya Nagarik Suraksha Sanhita, 2023 address inquiries and trials involving an accused who may be of unsound mind and incapable of making a defence. These provisions include assessment of the person's condition and, where the statutory criteria are met, postponement or other appropriate orders.

Inability to defend proceedings at present is distinct from the Section 22 BNS defence, which concerns the mental condition at the time of the alleged act. Sections 369 to 374 BNSS contain further provisions relating to release, resumption, acquittal and safe custody, as applicable.

Frequently Asked Questions

Is Section 84 IPC still applicable?

For conduct occurring from 1 July 2024, the corresponding substantive provision is Section 22 BNS. Section 84 IPC continues to matter in cases involving earlier conduct, subject to the governing transitional law.

Does every mental illness qualify for this defence?

No. The statutory test requires incapacity to know the nature of the act or its wrongfulness or illegality at the relevant time.

Who must establish the exception?

The accused bears the burden concerning circumstances bringing the case within the exception under Section 108 BSA, while the prosecution retains its obligation to prove the offence beyond reasonable doubt.

Is an insanity acquittal the same as an unconditional release?

No. The court must consider the applicable procedural provisions, including Section 373 and Section 374 BNSS, where relevant.

Official Statutory Sources

Updated: 28 October 2026. This article provides general legal information and does not replace advice on the facts of a particular case.