Illinois Prohibited Consensual Sexual Activity Laws

In general, non-consensual sexual contact is a criminal act. Old laws criminalized “sodomy” as a “crime against nature,” but today it is another form of sexual activity. If both parties consent, it is legal. If one party does not consent, the lack of consent makes it a criminal offense.

Any sexual act involving children, ranging from child pornography to sexual assault, can never be “consensual” because minors can't consent.

It may not matter if the parties commit consensual sexual activity. Some kinds of sexual contact are unlawful if committed in public even if both parties agree. In some cases, like statutory rape, one party can't consent because of their age or mental status. Legislators simply haven't removed some laws yet.

Antiquated Laws Still on the Books

• Fornication. § 5/11-40 Having “open and notorious” sexual intercourse with someone not the offender’s spouse. Fornication is a Class B misdemeanor
• Adultery. § 5/11-35 Having “open and notorious” sexual relations with another person if either party is married and both parties are aware of the fact. Adultery is a Class A misdemeanor

Although these remain sex offenses under Illinois law, they are almost never charged. But adultery can become a problem for the offending spouse during divorce proceedings. Adultery can result in the offending spouse paying higher spousal support or other penalties.

Sexual Activity and Age of Consent

In Illinois, the legal age of consent for sexual conduct is 17. Unlike other states, Illinois does not have “Romeo and Juliet laws” allowing a 17-year-old and 16-year-old to have sex. Under Illinois’ statutory rape laws, it is possible for two minors to commit statutory rape (§ 5/11-1.50).

If both parties are minors, the offense is a misdemeanor. If the perpetrator is an adult or in a position of authority, the offense is a felony.

Non-Consensual Sexual Conduct

Public acts committed for the sexual gratification of the offender do not have consent. Indeed, that is the purpose. A flasher never asks victims for consent before whipping open the trenchcoat. These offenses may cause little more than disgust or laughter, but the offender can receive serious penalties.

• Public indecency. Act in a public place consisting of “lewd exposure” done with intent to arouse the performer (§ 5/11-30). The offense is a Class A misdemeanor. After the third offense, or within 500 feet of a school, it is a Class 4 felony.
• Prostitution. Prostitution (§ 5/11-14) encompasses solicitation, loitering, trafficking, and promoting prostitution. Charges range from misdemeanors to felonies. If the offense involves a child, it becomes a Class X felony with a potential life sentence.

For more information, visit FindLaw's sex crimes section.

Get Legal Advice from an Illinois Criminal Defense Attorney

The line between non-consensual and consensual sex is not always clear. If you need help with an incident that may have crossed this line, contact an Illinois criminal defense attorney for legal help.