Part 1
GENERAL PART
Chapter 2
OFFENCE
Division 2
Preclusion of Unlawfulness
§ 31. Error concerning circumstance which precludes unlawfulness
(1) An intentional act is not unlawful if at the time of commission of the act the person erroneously assumes circumstances which would preclude the unlawfulness of the act. In such case, the person shall be punished for an offence committed through negligence in the cases provided by law.
(2) A person who at the time of commission of an act is unaware of the circumstances which objectively preclude the unlawfulness of the act shall be held liable for an attempt. In such case, the court may apply the provisions of § 60 of this Code.
Mistake of fact - national proceedings
EDIT.