delivered the opinion of the court:
Following a jury trial in the circuit court of Douglas County, defendant, Lonnie H. Jones, was convicted of attempt (aggravated criminal sexual abuse) (720 ILCS 5/8 — 4, 12 — 16(d) (West 1992)) and sentenced to a prison term of five years. The appellate court, in a divided opinion, affirmed. 276 Ill. App. 3d 1006. We allowed defendant’s petition for leave to appeal (155 Ill. 2d E. 315).
A criminal information, filed January 25, 1994, charged defendant with attempt (aggravated criminal sexual abuse). The information alleged that, with the intent to commit the offense of aggravated criminal sexual abuse, defendant "performed a substantial step toward the commission of that offense, in that he disrobed in the presence of [D.R.], who was at least 13 years of age but under 17 years of age at the time, stimulated his [own] penis to erection and requested the said [D.R.] to masturbate him to orgasm, for the purpose of the sexual gratification of the defendant; and that said defendant was at least 5 years older than [D.R.].”
At trial, the complainant, D.R., testified that he was born on January 18, 1977, and was 16 years and 10 months old on November 12, 1993. Around 7 p.m. that evening, he went to Chad Williams’ apartment in Newman for a party, after receiving an invitation from Williams and another friend, Matt Hutcherson. Defendant, whom D.R. had never met before, was at the apartment when the three arrived. The four men spent the evening drinking beer, with defendant purchasing an additional supply at some point.
Williams and Hutcherson had either fallen asleep or passed out in the living room by 11:45 p.m., and defendant went into the bedroom. D.R. testified that he could not sleep, so about 11:57 p.m. he knocked on the bedroom door, went in and began talking with defendant. After a while, defendant got undressed and sat naked on the floor with his back against the bed. The two continued talking, with D.R. sitting on the floor next to a wall, and then defendant asked if he could masturbate D.R. Defendant also asked D.R. to masturbate him. These requests made D.R. fearful, so he replied "No,” and started to leave the bedroom. D.R. testified that, at this point, defendant told him not to tell anyone about the incident "or otherwise he’d get me, and if he couldn’t, he had somebody that would.” D.R. then went into the living room and lay down next to his friend Williams, but did not leave the apartment because he was afraid defendant would come after him.
Under cross-examination, D.R. admitted that defendant had never touched him and that he had been free to leave at any time. D.R. stated that, out of embarrassment, he did not report the incident to anyone for several months. Eventually, he spoke to Police Chief Russell Stephens, but forgot to mention one of defendant’s two requests for sexual conduct. D.R. denied telling Stephens that defendant came out of the bedroom and took his clothes off in the living room, but admitted telling Stephens that defendant was masturbating himself when he talked to D.R. D.R. then conceded that in his April 15, 1994, statement to State’s Attorney Richard Broch, he said he had not been looking at defendant and could not tell whether or not defendant was touching himself or his penis.
City of Newman Police Chief Russell Stephens testified for the defense that he interviewed D.R. on January 21, 1994. D.R. told him that he was spending the night with Williams and Hutcherson in the apartment when defendant arrived. D.R. further stated that defendant approached him in the room where Williams and Hutcherson were sleeping, took off his clothes, obtained an erection, and asked D.R. to masturbate him. Stephens testified that D.R. gave no indication in his statement that defendant had threatened him. For the State, Stephens testified as to his opinion, based on his experience as a police officer, that defendant was 28 or 29 years old as of November 1993, and estimated that defendant was at least 10 years older than D.R.
Before this court, defendant challenges the sufficiency of the evidence supporting his conviction and contends that he did not receive a fair trial because the trial court: (1) erroneously refused his tendered jury instruction on the affirmative defense that he had a reasonable belief the complainant was 17 years of age or older; (2) erroneously refused his tendered instruction on the lesser included offense of public indecency based on lewd exposure; and (3) gave a misleading instruction on the definition of sexual conduct. We believe the affirmative defense instruction issue to be dispositive.
At trial, defense counsel tendered, and the trial court refused, the following instruction:
"It is a defense to the charge of aggravated criminal sexual abuse that the defendant reasonably believed [D.R] to be 17 years of age or older.” See Illinois Pattern Jury Instructions, Criminal, No. 11.64 (3d ed. 1992).
This instruction is based on section 12 — 17(b) of the Criminal Code of 1961 (720 ILCS 5/12 — 17(b) (West 1992)), which operates as an affirmative defense. See People v. Cora, 238 Ill. App. 3d 492, 499-500 (1992); People v. Brown, 171 Ill. App. 3d 391, 397-98 (1988). The appellate court majority below affirmed the trial court’s decision, stating: "On this record, we cannot say that the evidence presented by the State fairly raised the issue of the affirmative defense so as to require the trial judge to instruct the jury in this regard.” 276 Ill. App. 3d at 1009. We agree with the appellate court dissent that defendant’s instruction should have been given to the jury to consider and that it was reversible error to prevent defendant from presenting this defense by means of the tendered instruction. 276 Ill. App. 3d at 1011-13 (Cook, P.J., dissenting).
A defendant is entitled to an instruction on his theory of the case if there is some foundation for the instruction in the evidence, and if there is such evidence, it is an abuse of discretion for the trial court to refuse to so instruct the jury. People v. Crane, 145 Ill. 2d 520, 526 (1991). Very slight evidence upon a given theory of a case will justify the giving of an instruction. People v. Bratcher, 63 Ill. 2d 534, 540 (1976); see also People v. Moore, 250 Ill. App. 3d 906, 915 (1993); People v. Lyda, 190 Ill. App. 3d 540, 544 (1989). As the appellate court dissent noted: "In deciding whether to instruct on a certain theory, the court’s role is to determine whether there is some evidence supporting that theory; it is not the court’s role to weigh the evidence.” 276 Ill. App. 3d at 1012 (Cook, P.J., dissenting); see also Lyda, 190 Ill. App. 3d at 544.
In order to avail himself of the affirmative defense at issue, a defendant is required to produce some evidence at trial to demonstrate the existence of a reasonable belief that the victim was 17 years of age or older. See People v. Kite, 153 Ill. 2d 40, 44-45 (1992); Cora, 238 Ill. App. 3d at 500. However, the defendant will be excused from presenting any evidence where the evidence presented by the State raises the issue of the affirmative defense. See Cora, 238 Ill. App. 3d at 500; 720 ILCS 5/3 — 2(a) (West 1992). In essence, unless the evidence before the trial court is so clear and convincing as to permit the court to find as a matter of law that there is no affirmative defense, the issue of whether a defendant should be relieved of criminal liability by reason of his affirmative defense must be determined by the jury with proper instruction as to the applicable law. See Lyda, 190 Ill. App. 3d at 545.
In the case at bar, the State’s evidence alone was sufficient to raise the issue of defendant’s reasonable belief that D.R. was 17 years of age or older. At the time of the offense, D.R. was 16 years and 10 months old, and defendant did not know D.R. prior to the incident. Further, D.R. was consuming alcohol, an activity restricted to adults, when defendant met him, and D.R. was apparently free to stay overnight at his friend’s apartment. Additionally, the jury saw D.R. testify and was able to observe his appearance and demeanor so as to determine whether there was a reasonable doubt that defendant believed D.R. to be 17 years old.
The appellate court majority’s reliance on People v. Lemons, 229 Ill. App. 3d 645 (1992), for its holding is misplaced. As the dissent noted:
"The Lemons defendant did not appeal any failure to instruct, but argued the State failed to prove beyond a reasonable doubt his belief as to the victim’s age. The appellate court held a rational trier of fact could have found against defendant on that issue (a holding unavailable in the present case because the trier of fact was not instructed on the issue), but went on in dicta to indicate the evidence was not sufficient to impose on the State the burden of proving that defendant’s belief was unreasonable.” 276 Ill. App. 3d at 1012 (Cook, P.J., dissenting).
Lemons is also distinguishable on its facts, where the victim was only 14 and there was evidence that the defendant was told the victim’s age before the offense occurred. See Lemons, 229 Ill. App. 3d at 652.
As earlier stated, defendant was not required to testify or offer any evidence making his reasonable belief of the victim’s age an issue. The circumstantial evidence presented by the State was sufficient to raise the affirmative defense. Indeed, mental states are not commonly proved by direct evidence, but are more often inferred from the character of a defendant’s acts and the circumstances surrounding the commission of the offense. People v. Terrell, 132 Ill. 2d 178, 204 (1989); see also People v. Summers, 202 Ill. App. 3d 1, 10 (1990).
We conclude that defendant was entitled to the benefit of the affirmative defense as shown by the evidence in the record. The State then would have to prove beyond a reasonable doubt that defendant did not reasonably believe the victim to be 17 years of age or over. 720 ILCS 5/3 — 2(b) (West 1992). Ultimately, it was for the jury to determine whether defendant had a reasonable belief that the victim had attained the age of 17 years. Absent defendant’s tendered instruction, the jury lacked the necessary tools to analyze the evidence fully and to reach a verdict based on those facts. See Lyda, 190 Ill. App. 3d at 546. The resulting denial of due process requires that defendant be granted a new trial.
Defendant also contends that the evidence was insufficient to sustain his conviction for attempt (aggravated criminal sexual abuse), and this question must be decided in order to remove the risk of subjecting defendant to double jeopardy. People v. Taylor, 76 Ill. 2d 289, 309 (1979). Defendant argues that the offense of aggravated criminal sexual abuse requires an act of sexual conduct with the victim (720 ILCS 12 — 16(d) (West 1992)), and that the mere request for sexual conduct with the victim does not constitute a "substantial step” towards the commission of that offense necessary to establish attempt (720 ILCS 5/8 — 4(a) (West 1992)). However, D.R testified that defendant "[got] completely undressed” and then requested that they engage in acts of mutual masturbation. After careful consideration, we agree with the appellate court that this act of exposure, when added to the request for sexual conduct, was sufficient to constitute a substantial step notwithstanding the lack of any actual contact between defendant and the victim. 276 Ill. App. 3d at 1008-09, citing People v. Brewer, 118 Ill. App. 3d 189 (1983). We therefore believe the evidence at trial was sufficient for the jury to conclude that defendant was guilty beyond a reasonable doubt, but note that this is not a finding that would be binding on retrial. Taylor, 76 Ill. 2d at 309-10.
Finally, we consider defendant’s arguments regarding other alleged erroneous instructions, to prevent these questions from arising on retrial. Defendant contends that the trial court erred in refusing his tendered instruction on the lesser included offense of public indecency based on lewd exposure (720 ILCS 5/11 — 9(a)(2) (West 1992)). The appellate court concluded that public indecency based on lewd exposure was not an included offense of attempt (aggravated criminal sexual abuse). 276 Ill. App. 3d at 1011.
In People v. Novak, 163 Ill. 2d 93 (1994), we reaffirmed our preference for the charging instrument approach in identifying lesser included offenses. Under this approach, an offense is deemed to be a lesser included offense if it is described by the charging instrument. Novak, 163 Ill. 2d at 107. At a minimum, the instrument charging the greater offense must " 'set out the main outline of the lesser offense.’ ” Novak, 163 Ill. 2d at 107, quoting People v. Bryant, 113 Illl. 2d 497, 505 (1986). Contrary to the appellate court’s holding, we find that the lesser included offense at issue was adequately described by the charging instrument. It is clear from the language of the information, as set forth above, that the "main outline” of the offense of public indecency based on lewd exposure can be found therein. See 720 ILCS 5/11 — 9 (West 1992). However, "[t]he identification of a lesser included offense does not automatically give rise to a correlative right to have the jury instructed on the lesser offense.” Novak, 163 Ill. 2d at 108.
Before a defendant is entitled to a lesser included offense instruction, the trial court must examine the evidence presented and determine if it would "permit a jury rationally to find the defendant guilty of the lesser included offense and acquit him or her of the greater offense.” Novak, 163 Ill. 2d at 108. In the case at bar, there was no evidence presented, by either the State or defense, that the defendant’s act of exposure was "done with intent to arouse or to satisfy the sexual desire of the [defendant].” 720 ILCS 5/11 — 9(a)(2) (West 1992). Rather, the evidence showed that defendant disrobed in the hope of achieving sexual gratification through sexual conduct with D.R. Thus, the trial court did not err in refusing to give the lesser included offense instruction, because the jury could not have rationally convicted defendant of public indecency based on lewd exposure where it was not established that that act was done with the intent to arouse or satisfy defendant’s sexual desire. See People v. Harris, 205 Ill. App. 3d 873, 876 (1990).
Defendant also contends that the trial court erred when it gave a misleading and incorrect instruction on the definition of sexual conduct. For the reasons stated by the appellate court (276 Ill. App. 3d at 1010), we agree with defendant and trust that this error will not be repeated on retrial.
For the foregoing reasons, the judgments of the circuit and appellate courts are reversed and this cause is remanded for a new trial consistent with the views expressed herein.
Reversed and remanded.