the constitution of illinois is the foremost source of state law. legislation is enacted by the illinois general assembly, published in the "laws of illinois", and codified in the "illinois compiled statutes" (ilcs). state agencies publish regulations (sometimes called administrative law) in the "illinois register", which are in turn codified in the "illinois administrative code". illinois's legal system is based on common law, which is interpreted by case law through the decisions of the supreme court and the appellate court, which are published on the website of the supreme court. counties, townships, cities, and villages may also promulgate local ordinances. there are also several sources of persuasive authority, which are not binding authority but are useful to lawyers and judges insofar as they help to clarify the current state of the law.