Explanation:

Mistake of fact or ignorance of fact is wider section 76 is generally a defence. The justification for exemption on the ground of mistake of fact and ignorance of fact is based on the principle that a man who is mistaken or ignorant about the existence of a fact 'cannot form the necessary mens rea (intention) to constitute a crime and is therefore he is not responsible in law for his deeds.

Section 79 is complimentary to section 76. It exempts a person from criminal liability, in those cases where by reason ofmistake (or ignorance) of fact in good faith, and not by reason of mistake of law, a man considers himself justified by law to do an act in a particular way