a. Ignorance or mistake as to a matter of fact or law is a defense if the defendant reasonably arrived at the conclusion underlying the mistake and:
(1) It negatives the culpable mental state required to establish the offense; or
(2) The law provides that the state of mind established by such ignorance or mistake constitutes a defense.
b. Although ignorance or mistake would otherwise afford a defense to the offense charged, the defense is not available if the defendant would be guilty of another offense had the situation been as he supposed. In such case, however, the ignorance or mistake of the defendant shall reduce the grade and degree of the offense of which he may be convicted to those of the offense of which he would be guilty had the situation been as he supposed.
c. A belief that conduct does not legally constitute an offense is a defense to a prosecution for that offense based upon such conduct when:
(1) The statute defining the offense is not known to the actor and has not been published or otherwise reasonably made available prior to the conduct alleged; or
(2) The actor acts in reasonable reliance upon an official statement of the law, afterward determined to be invalid or erroneous, contained in (a) a statute, (b) judicial decision, opinion, judgment, or rule, (c) an administrative order or grant of permission, or (d) an official interpretation of the public officer or body charged by law with responsibility for the interpretation, administration or enforcement of the law defining the offense; or
(3) The actor otherwise diligently pursues all means available to ascertain the meaning and application of the offense to his conduct and honestly and in good faith concludes his conduct is not an offense in circumstances in which a law-abiding and prudent person would also so conclude.
The defendant must prove a defense arising under subsection c. of this section by clear and convincing evidence.