Here is a link to a website that claims to publish current Illinois law concerning the age of consent.
http://moraloutrage.net/staticpages/index.php?page=Illinois
According to the information, the age of consent in Illinois is 17. So, if this information is truly accurate, then a 17-year-old may consent to sexual activity. There are several exceptions:
"(a) The accused commits criminal sexual assault if he or she:
(1) commits an act of sexual penetration by the use of force or threat of force; or
(2) commits an act of sexual penetration and the accused knew that the victim was unable to understand the nature of the act or was unable to give knowing consent; or
(3) commits an act of sexual penetration with a victim who was under 18 years of age when the act was committed and the accused was a family member; or
(4) commits an act of sexual penetration with a victim who was at least 13 years of age but under 18 years of age when the act was committed and the accused was 17 years of age or over and held a position of trust, authority or supervision in relation to the victim."
As for the extent of physical activity considered legal, the following link states that "In all states, dating, hugging, holding hands and kissing are not illegal. In some states, fondling, groping through the clothes or other such things known as "3rd base" is illegal."
http://www.ageofconsent.us/
Unless the 17-year-old is unable to give consent, or the 22-year-old is a family member or person of trust and supervision (for example, a teacher), then the above information is inconsequential, if all of this information is current and accurate.
Here is the link to the Illinois General Assembly Criminal Code. It's very long, but you can verify the above information.
Hope it helps.
