CHAPTER III—GENERAL RULES AS TO CRIMINAL RESPONSIBILITY
9. Mistake of fact.
(1) A person who does or omits to do an act under an honest and reasonable, but mistaken, belief in the existence of any state of things is not criminally responsible for the act or omission to any greater extent than if the real state of things had been such as he or she believed to exist.
(2) The operation of this section may be excluded by the express or implied provisions of the law relating to the subject .
1. A mistake of fact shall be a ground for excluding criminal responsibility only if it negates the mental element required by the crime.