Legal Question in Family Law in Illinois

Only the states Attorney presses criminal charges for adultery. i do not believe that there has been any such charge placed in over 50 years. If you want to seek a divorce on the grounds of adultery, you are entitled to do so, but it does not give a leg up on anything and in fact may adversely affect you - judges do not like such public airing as it is on the record forever.

I believe that adultery is still a crime in Illinois, however it is a Class A misdemeanor. It would be up to the State's Attorney to press charges against your spouse.