CHAPTER IV
GENERAL EXCEPTIONS
Act done by a person bound, or by mistake of fact believing himself bound by law
76. Nothing is an offence which is done by a person who is, 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, bound by law to do it.
Illustrations
(a) A, a soldier, fires on a mob by the order of his superior officer, in conformity with the commands of the law. A has committed no offence.
(b) A, an officer of a court of justice, being ordered by that court to arrest Y, and, after due enquiry, believing Z to be Y, arrest Z. A has committed no offence.
Mistake of fact - national proceedings
EDIT.