Facts of the Case

A is charged with committing the murder of B.
During the trial, A raises the defence that he was of unsound mind at the time of the incident and therefore:

• He did not know the nature of the act, or
• He did not know that what he was doing was either wrong or contrary to law.

A claims protection under the general exception of insanity.

The question arises: Who must prove the plea of unsoundness of mind?

Issues in the Case

1. Whether the burden of proving unsoundness of mind (insanity) lies on the accused or the prosecution.
2. Whether Section 105 of the Indian Evidence Act applies.
3. Whether the prosecution must prove mens rea if the accused raises insanity as a defence.
4. What standard of proof is required to establish the defence of insanity.

Legal Principles Covered

A. Section 105 – Burden of Proving Exceptions (Indian Evidence Act, 1872)

Section 105 states:

• When a person is accused of an offence,
• And he claims the benefit of any general exception under the IPC (such as insanity under Section 84 IPC),
• The burden of proving the existence of such circumstances lies upon the accused.

Effect:
A must prove that he was of unsound mind at the time of committing the offence.

The prosecution does not have to prove sanity; it must only prove the ingredients of the offence.

B. Section 84 – Unsoundness of Mind (IPC)

Section 84 IPC provides that:

A person is not liable for an act if, due to unsoundness of mind, he was incapable of:

• Knowing the nature of the act, or
• That the act was wrong or contrary to law.

The defence must relate to the exact time of the act, not before or after.

C. Standard of Proof Required

• The accused does not have to prove insanity beyond reasonable doubt.
• He must only create a reasonable probability of his unsoundness of mind.
• If this probability exists, and reasonable doubt is created about mens rea, the benefit of doubt goes to the accused.

D. Case Law

Courts have consistently held:

• The burden lies on the accused (Section 105 Evidence Act).
• When reasonable doubt is created about mental capacity at the time of offence, the accused gets the benefit of Section 84 IPC.

The prosecution must still prove the physical act of murder and the required mental intent, unless disproved by credible evidence of insanity.

Possible Judgment

1. The burden of proof lies on the accused (A) to prove the existence of circumstances that bring his case under the general exception of unsoundness of mind under Section 84 IPC.
2. This is mandated by Section 105 of the Indian Evidence Act, which clearly states that the accused must prove any exception he claims.
3. The prosecution is only required to prove the offence and the intention beyond reasonable doubt—not to prove that A was sane.
4. If A produces sufficient evidence (medical records, past history, conduct before/after incident, expert testimony) to establish a reasonable probability of insanity at the time of the act, he may get the benefit of the doubt.
5. If A fails to prove insanity, the defence under Section 84 IPC will not apply, and he will be convicted.

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