Illinois does not have a true “Romeo and Juliet law.” No rule erases the crime just because two people are close in age and the younger one agreed. What Illinois has instead is a narrow affirmative defense (a legal argument that can reduce a charge, not one that makes it disappear) for certain close-in-age situations. It also has a sliding scale where the exact ages decide whether you’re looking at a misdemeanor, a felony, or one of the most serious charges in the state’s criminal code.
That distinction matters enormously, and it’s where a lot of people get a dangerously wrong first impression. This article walks through what Illinois’ age-of-consent law actually says, when the close-in-age exception applies and when it doesn’t, how the specific ages change the charge, whether sex-offender registration is on the table, and whether a mistake about age changes anything. Every legal point below is tied to the Illinois statute or case that controls it.
What is the age of consent in Illinois?
The age of consent in Illinois is 17. A person under 17 cannot legally give consent to sexual conduct or penetration, no matter how willing they were or how the relationship felt to both people (720 ILCS 5/11-1.70).
There’s a critical exception baked into that number. The age of consent rises to 18 whenever the older person holds a position of trust, authority, or supervision over the younger one. Under that rule, a 17-year-old who can legally consent to a peer cannot legally consent to their coach, teacher, tutor, boss, or anyone in a similar role. Keep that second number in your back pocket. It’s the single detail that turns a defensible case into a much harder one, and we’ll come back to it.
Illinois also splits these offenses by what happened. The law separates “sexual penetration” (any contact, however slight, involving the sex organs, mouth, or anus) from “sexual conduct” (knowing touching of the sex organs, anus, or breast for sexual gratification), and defines both in 720 ILCS 5/11-0.1. Penetration cases are charged more severely than touching cases, so the same age gap can land in very different places depending on the conduct alleged.
What does Illinois’ close-in-age exception actually cover?
The close-in-age exception is a defense that can knock a felony down toward a Class A misdemeanor. It is not a free pass, and it does not decriminalize what happened. Under 720 ILCS 5/11-1.50, criminal sexual abuse is charged as a Class A misdemeanor (rather than a felony) when the older person is less than five years older than a younger person aged 13 to 16, and the contact was consensual.
Read that carefully, because the fine print is the whole game:
- It reduces the charge. It doesn’t erase it. Even the best-case outcome here is still a criminal charge with a conviction on the line.
- It has hard boundaries: the younger person must be at least 13, the age gap must be under five years, and the older person is generally under 21.
- It evaporates if the older person held a position of trust or authority, because then the age of consent was 18 to begin with (720 ILCS 5/11-1.60).
So when people say “Romeo and Juliet law,” what they’re really pointing at is this reduction, a way to argue the situation down, not out. Illinois courts have upheld the state’s sex-offense statutes against constitutional challenge, so this is settled ground, not a gray area waiting to be exploited.
The charge depends on the exact ages. So where does your situation fall?
Illinois runs a severity ladder, and the younger person’s age is the rung you land on. The same act can be a misdemeanor, a mid-level felony, or a Class X felony depending on two numbers: how old the younger person was, and how big the gap was.
- Younger person 13–16, gap under 5 years, consensual. This is the close-in-age zone: criminal sexual abuse chargeable as a Class A misdemeanor under 720 ILCS 5/11-1.50.
- Younger person 13–16, older person at least 17, gap of 5 years or more. This becomes Aggravated Criminal Sexual Abuse, a Class 2 felony carrying 3–7 years under 720 ILCS 5/11-1.60(d). The five-year line is a cliff, not a slope. A gap of four years and eleven months is a different case than five years and one day.
- A position of trust or authority is involved. The offense jumps to a Class 1 felony (4–15 years) under 720 ILCS 5/11-1.60(f), regardless of how small the age gap is.
- Younger person under 13. The close-in-age exception does not exist here at all. Penetration with a child under 13 is Predatory Criminal Sexual Assault of a Child, a Class X felony carrying 6–60 years (720 ILCS 5/11-1.40). A second offense is punishable by natural life. In under-13 cases, Illinois courts have affirmed convictions on proof of the sexual act and the ages alone (People v. Sanders, 191 Ill. App. 3d 483 (1989)).
If your facts sit near one of those boundaries, the exact birthdates and the calendar aren’t details: they’re the case.
Does it matter that it was consensual, or that there was no force or injury?
For an age-based charge, no, and this is the hardest thing for most people to absorb. In these cases the prosecutor generally does not have to prove force, resistance, or any physical injury. The younger person’s age is what makes the conduct illegal. There are no bruises to look for and no struggle to reconstruct. “But they wanted to” and “nothing violent happened” are true statements that don’t reach the element the State actually has to prove.
That’s the opposite of how a force-based sexual assault case works, where consent is genuinely contested. Here, a person under 17 is legally incapable of consenting, so the willingness that feels central to the people involved is legally beside the point. Illinois does generally require some mental state. Where a statute doesn’t spell one out, courts imply a mental state of intent, knowledge, or recklessness (People v. Terrell, 132 Ill. 2d 178 (1989); People v. Anderson, 2024 IL App (5th) 220775-U). But in age-based cases that rarely gives a defendant the opening they’re hoping for. The real defense in these cases usually isn’t “it was consensual.” It’s the ages, the gap, the conduct alleged, and the reliability of the State’s proof on each.
What if he genuinely didn’t know her real age?
A mistake about the younger person’s age is a defense only in a narrow window, and it collapses entirely at the youngest ages. Illinois allows a reasonable-mistake-of-age defense when the younger person was 13 to 16 and the older person was less than five years older, the same close-in-age zone from above.
Outside that window, it’s not available. If the younger person was under 13, it does not matter what they said, what their ID showed, or how old they looked. Mistake of age is off the table, and Illinois law is unforgiving on that point. Even inside the window, “I thought they were older” is not magic words. It has to be a reasonable belief a court will accept, not just an honest one. This is exactly the kind of assumption that feels like a lifeline and turns out not to be one. That’s why it should be tested by a lawyer before anyone leans on it.
What could make this much worse: the position-of-trust trap
The fastest way a close-in-age case turns into a serious felony is a supervisory relationship between the two people. When the older person had authority over the younger one, the age of consent was 18, not 17. So the close-in-age defense never applies, and the charge climbs to a Class 1 felony (4–15 years) under 720 ILCS 5/11-1.60(f).
“Position of trust, authority, or supervision” can reach further than people expect, and it’s easy to overlook until it’s too late. If any authority relationship exists in your facts, assume the prosecutor already sees it. Don’t build any hope around the close-in-age exception until a lawyer confirms it survives.
Will he have to register as a sex offender?
For a felony conviction under these statutes, yes, sex-offender registration is a real and central consequence, and it’s usually the fear underneath the whole search. Illinois’ registration terms are set by 730 ILCS 150/7: most sex offenders register for 10 years, while those classified as “sexual predators” register for life (730 ILCS 150/2).
Registration is not a formality. It’s a public listing (Illinois has more than 18,000 registered sex offenders) that shapes where a person can live, work, and go. It follows them. This is precisely why the exact offense of conviction carries so much weight. In Illinois, registration attaches to specific enumerated offenses, not to whether a conviction is a felony or a misdemeanor. A misdemeanor criminal sexual abuse conviction can still be a registrable offense. What the conviction is drives both your penalty exposure and, for the offenses that do require registration, whether you register for 10 years as a “sex offender” or for life as a “sexual predator” (730 ILCS 150/2, 150/7). Because those consequences turn on the precise offense rather than a felony-versus-misdemeanor label, whether registration applies to your situation is a question to work through with counsel, offense by offense. And it’s worth knowing the sentencing picture isn’t automatically prison. Statewide, about 67% of people convicted of Class 1 through 4 felonies receive probation rather than incarceration. Even so, registration and other consequences can still apply. That’s a reason to fight for the right classification, not a reason to relax.
What to do right now
If this situation is live, the most important move is to get the exact facts in front of a lawyer before anyone assumes how it will turn out. Three things drive everything:
- Pin down the exact ages and the gap. Whether you land in the close-in-age misdemeanor zone, the Class 2 felony tier, or something more serious depends on the precise birthdates, down to whether the gap is under or over five years.
- Check for any position of trust or authority. If one exists, the close-in-age defense may not apply at all, and the potential penalties change dramatically.
- Don’t assume the “Romeo and Juliet” reduction is available. Whether it applies, and whether it can hold a case at a misdemeanor rather than a registrable felony, is a call that depends on the specific facts, not a given.
These cases depend on precision: the exact ages, the size of the gap, the conduct alleged, and whether any authority relationship exists. That’s the kind of defense DRD Law, LLC in Chicago is built for. Founding partner David R. Drwencke spent nearly seven years as a judicial law clerk in Oakland County Circuit Court, watching hundreds of trials and learning firsthand how judges weigh exactly these elements, and he’s carried that evidence-based approach through 565+ criminal defense cases and recognition as an Illinois Super Lawyers Rising Star every year from 2019 through 2026. In close-in-age and sex-offense matters, where the difference between a Class A misdemeanor and a registrable felony can come down to a single birthday, that kind of granular, judge’s-eye reading of the facts is the whole ballgame.
DRD Law, LLC is located at 332 S. Michigan Avenue, Suite 900, Chicago, IL 60604. If you or someone you care about is facing this, reach out for a confidential consultation.
This article is general legal information about Illinois law, not legal advice. Reading it does not create an attorney-client relationship with DRD Law, LLC or any of its attorneys. Every case turns on its own facts. Consult a licensed Illinois criminal defense attorney about your specific situation.
