The most I can find is the Illinois Criminal Code of 1961, Title III, Part D, Article 24, which is a lengthy read concerning weapons in the state. Try Article 24, section 1-a-3, which authorizes the carrying of a non-lethal noxious "liquid gas" (not sure what that is!) designed solely for self-defense. There are provisions for carrying chemical, non-lethal weapons for self-defense by persons of at least 18 years of age, with a few restrictions on where these may be possessed.
Now, many states do not have laws on the books specifically
permitting certain acts, they are simply considered lawful because there are no laws
prohibiting them. That would, if the case with this, be why you cannot find a specific code or statute allowing pyrotechnic-powered self-defense chemical weapons. Because of the pyrotechnic mechanism of the Pepper-Blaster II by Kimber, there might be some as-yet undiscovered issue with whether or not it "fits" the legislative intent of a "self-defense" spray. But, for now, it
appears legal due to the lack of a specific prohibition of it.
My check started at the URL below...
http://www.ilga.gov/legislation/ilc...hapterID=53&SeqStart=68200000&SeqEnd=71300000