(b) It is unlawful for any person knowingly to manufacture, distribute, advertise, or possess with intent to manufacture or distribute a look-alike substance. Possession of a drug listed in Schedule I or Schedule II is the most serious possession offenses that one can face in Illinois, and is a felony charge.The law states that it is unlawful for a person to be in possession of a controlled substance, a counterfeit substance or an analog. Unlawful search and seizure. Sometimes, the police obtain drugs through illegal search or seizure, such as without a warrant or probable cause. Possession of illegal drugs in Illinois can mean jail or prison time, depending on the amount possessed, the type of drug, and a person's criminal record. In this blog post, we will explore the relevant statutes, penalties, and key considerations associated with the possession of controlled substances in Illinois. But if you successfully complete this type of probation, when you go back to court 2 years later the case will be dismissed and the charges will be thrown out. Section 4 (Possession). Unlawful for any person knowingly to possess cannabis in the following amounts.