Section 720 ILCS 5/3-2 - Affirmative defense(a) "Affirmative defense" means that unless the State's evidence raises the issue involving the alleged defense, the defendant, to raise the issue, must present some evidence thereon.(b) If the issue involved in an affirmative defense, other than insanity, is raised then the State must sustain the burden of proving the defendant guilty beyond a reasonable doubt as to that issue together with all the other elements of the offense. If the affirmative defense of insanity is raised, the defendant bears the burden of proving by clear and convincing evidence his insanity at the time of the offense.P.A. 89-404, eff. 8/20/1995; 90-593, eff. 6/19/1998.