(720 ILCS 5/4-8)
(from Ch. 38, par. 4-8)
Ignorance or mistake.
(a) A person's ignorance or mistake as to a matter of either fact or
law, except as provided in Section 4-3(c) above, is a defense if it
negatives the existence of the mental state which the statute prescribes
with respect to an element of the offense.
(b) A person's reasonable belief that his conduct does not constitute an
offense is a defense if:
(1) the offense is defined by an administrative
regulation or order which is not known to him and has not been published or otherwise made reasonably available to him, and he could not have acquired such knowledge by the exercise of due diligence pursuant to facts known to him; or
(2) he acts in reliance upon a statute which later is
determined to be invalid; or
(3) he acts in reliance upon an order or opinion of
an Illinois Appellate or Supreme Court, or a United States appellate court later overruled or reversed; or
(4) he acts in reliance upon an official
interpretation of the statute, regulation or order defining the offense, made by a public officer or agency legally authorized to interpret such statute.
(c) Although a person's ignorance or mistake of fact or law, or
reasonable belief, described in this Section 4-8 is a defense to the
offense charged, he may be convicted of an included offense of which he
would be guilty if the fact or law were as he believed it to be.
(d) A defense based upon this Section 4-8 is an affirmative defense.
(Source: P.A. 98-463, eff. 8-16-13.)