Here is the answer I found on the web for the state of Illinois:
Q: I have a question about tinted windows. I have a problem with my eyes called photo phobic and need to have the front side window of my vehicle tinted. Is there a way to do that? I cannot find anyone who will tint the window. I checked Illinois vehicle code # 5/12 503(a) and was unable to find any kind of a solution. Where can I go to get help for a problem like mine? Will a doctor's excuse do? I really need your help in finding an answer to my problem.
P.C. of Chillicothe
A: The short answer to your question is no, you may not have the windows of your vehicle tinted even if you have a doctor's excuse.
However, a spokesman at Illinois Secretary of State Jesse White's office said that if you were to purchase a car that already had a tinted driver's side window, you could drive it, but you must have a written order from your doctor.
He said the law that prohibits the tinting of the window adjacent to the driver's seat is Public Act 90-389. It was passed in 1998. He said that means your car would have to be older than a 1998 model for the tint to be legal.
He also said that same public act says that as of Jan. 1, 2008, the tint must be removed from all vehicles and will not be allowed even with a doctor's excuse.
So, the answer is NO for the driver's and passenger's windows......