BNS Section 17 — Act done by a person justified, or by mistake of fact believing himself justified, by law

Summary

Nothing is an offence if the person doing the act is justified by law in doing it. The same protection applies if the person, acting in good faith, believes they are justified by law because of a mistake of fact — not because of a mistake of law. In other words, a wrong belief about what the law says does not help, but a wrong belief about the facts can.

The illustration shows this: A sees Z commit what looks like a murder. A, using the power the law gives to anyone to arrest a murderer caught in the act, seizes Z to hand Z over to the authorities. Even if it later turns out Z was acting in self-defence, A has committed no offence because A acted in good faith on a mistake of fact.

Official Text

Nothing is an offence which is done by any person who is justified by law, or who by reason of a mistake of fact and not by reason of a mistake of law in good faith, believes himself to be justified by law, in doing it.

Illustration. A sees Z commit what appears to A to be a murder. A, in the exercise, to the best of his judgment exerted in good faith, of the power which the law gives to all persons of apprehending murderers in the fact, seizes Z, in order to bring Z before the proper authorities. A has committed no offence, though it may turn out that Z was acting in self-defence.

Related Judgments

• SC (2025) Vol.3 p.1309 — Supreme Court of India (2025)
• SC (2025) Vol.11 p.291 — Supreme Court of India (2025)
• SC (2025) Vol.3 p.1531 — Supreme Court of India (2025)
• SC (2025) Vol.6 p.280 — Supreme Court of India (2025)
• SC (2024) Vol.8 p.670 — Supreme Court of India (2024)
• SC (2025) Vol.4 p.2730 — Supreme Court of India (2025)
• SC (2024) Vol.6 p.129 — Supreme Court of India (2024)
• SC (2025) Vol.2 p.80 — Supreme Court of India (2025)

Old <-> New Code Mapping

• IPC §79 — Act done by a person justified, or by mistake of fact believing himself justified, by law