Section 17: Nothing is an offence which is done by any person who is justified by law, or who Act done by a
by reason of a mistake of fact and not by reason of a mistake of law in good faith, believes person justified,
or by mistake of
himself to be justified by law, in doing it. fact believing
himself justified,
Illustration. by law.
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.