GENERAL PART
Chapter Three
GENERAL PROVISIONS ON CRIMINAL OFFENCE
2. Guilt and Punishability of Perpetrators
Mistake of Law
Article 31
(1) The perpetrator of a criminal offence shall not be held to be liable under criminal law if, for reasons which can be justified, he did not know that such an offence was unlawful.
(2) There are no justified reasons referred to in paragraph 1 of this Article if the perpetrator was not aware of legal regulations, with which he could have familiarised himself under the same conditions as other people in his broader environment, or he should have known special legal regulations in relation to his work, role, or general position.
(3) If the perpetrator committed a criminal offence deemed as a mistake of law, which he could have avoided, the court may reduce the sentence.
Mistake of law - national proceedings
EDIT.