Statutes are laws passed by state legislatures (state laws) and by the United States Congress (federal laws). Statutes are one of the primary sources of law in the United States (sometimes referred to as statutory law) and cover a wide variety of legal topics. Courts often rely on statutes to resolve legal disputes (lawsuits) by applying the relevant statutes to the particular set of factual circumstances underlying the dispute.

Courts generally seek the clear and plain meaning of a statute, and if the court finds a statute ambiguous or “ambiguous on its face” (looking only at the words as written) the court may attempt to determine what the legislature intended in enacting the statute—known as legislative intent.

Related statutes are sometimes compiled in groups and referred to as codes—such as the penal code, the family code, or the code of civil procedure. Statutes may be amended (changed) or repealed (eliminated) by the legislature or Congress or declared unconstitutional (and thus unenforceable) by a court.

In Illinois, as in other states, statutes are laws enacted by the state legislature, known as the Illinois General Assembly, which includes the Illinois House of Representatives and the Illinois Senate. These statutes address a wide range of legal topics and are essential for the governance of state-related matters. Similarly, federal laws are statutes passed by the United States Congress and apply nationwide. Illinois courts interpret and apply these statutes to resolve legal disputes by looking for the clear and plain meaning of the language used in the statutes. If a statute is found to be ambiguous, courts may look into legislative intent to ascertain what the lawmakers meant when they passed the law. Illinois has various codes that compile related statutes, such as the Illinois Compiled Statutes (ILCS), which include the Criminal Code, Civil Code, and others. Statutes can be updated or amended by the legislature, and in some cases, they may be repealed or declared unconstitutional by the judiciary, rendering them unenforceable.