|Editor||Illinois Legislative Reference Bureau|
The Illinois Compiled Statutes (ILCS) are the codified statutes of a general and permanent nature of Illinois.   The compilation organizes the general Acts of Illinois into 67 chapters arranged within 9 major topic areas.  The Illinois Legislative Reference Bureau (LRB) makes additions, deletions, and changes to ILCS (for example, when new acts become law or existing acts are repealed) by filing documents as provided in Public Act 87-1005. 
The compilation is an official compilation by the state and is entirely in the public domain for purposes of federal copyright law; anyone may publish the statutes.  There is no official version of the ILCS, but there are several unofficial versions: Illinois State Bar Association's/ West's Illinois Compiled Statutes, West's Smith–Hurd Illinois Compiled Statutes Annotated, and LexisNexis's Illinois Compiled Statutes Annotated. 
Illinois officially revised its laws in 1827-29, 1833, 1845, and 1874.  In those revisions, bills were passed arranging the laws as alphabetical chapters.  (The 1819 session laws can also be considered a revision of the laws in some respects. ) Over time, the alphabetical arrangement of the 1874 Illinois Revised Statutes became less useful as some chapters had become huge, unwieldy, and disorganized by the addition of new acts.  The Illinois Supreme Court, among others, had pointed out the confusion caused by the poor organization of the outdated Illinois Revised Statutes, and in its 1988 and 1989 annual reports to the General Assembly recommended consideration of recodification. 
The 1874 Illinois Revised Statutes were an official arrangement of the statutes by the state in Illinois, but the state did not maintain the organizational scheme.  When a new act became law and needed to be placed within the framework of the Illinois Revised Statutes, that task was left to private publishers, but the publishers were not consistent.  One publisher might place a new act in one chapter and another publisher place the same new act in another chapter, and even if two publishers placed the act in the same chapter, they each might assign different paragraph numbers.  To solve the confusion and decrease the expense to its members, the Illinois State Bar Association decided in the 1930s to endorse the edition of a single publisher and to encourage all of its members to use only that edition.  The Bar Association's endorsement solved those problems, but it created another problem: a single publisher making editorial decisions as to where to place new acts in the chapters of the Illinois Revised Statutes allowed that publisher to assert a copyright interest in the arrangement of the Illinois Revised Statutes and to effectively prevent other publishers from entering the market.  That publisher was West Publishing Company.  Moreover, because the state had not maintained the organization and numbering of the Illinois Revised Statutes, it was an unofficial compilation of the statutes. 
In the late 1980s, a dispute arose between West, which claimed a copyright interest, and Mead Data Central (then the owner of the LexisNexis research services), which wanted to publish the Illinois Revised Statutes.  The dispute spilled over into the General Assembly and became a heavily lobbied issue, and as a result, in 1987 the General Assembly passed House Bill 1924, which attempted to make the arrangement of the Illinois Revised Statutes official and to put the arrangement into the public domain for purposes of federal copyright law.  Governor James Thompson vetoed the bill, stating that he feared it would embroil the state in costly copyright litigation.  In 1988, the General Assembly passed House Bill 3896, which had the same provisions as House Bill 1924, and the Governor again vetoed the bill.  West and Mead later settled their dispute. 
In 1989 the General Assembly passed House Bill 757, which became Public Act 86-523.  That act directed the LRB to submit to the General Assembly a plan for the comprehensive and systematic codification of the statutory law.   A Preliminary Plan dated November 29, 1990 was submitted.  LRB received numerous suggestions from government officials and agencies, bar associations and other private organizations, publishers, and others, and in light of those suggestions, LRB submitted a Revised Plan dated October 22, 1991.  The Revised Plan suggested organizing the nearly 2,000 acts into 67 chapters arranged within 9 major topic areas.  The Board of the Legislative Reference Bureau held a public hearing on November 6, 1991 concerning the Preliminary and Revised Plans, and those testifying at the hearing generally expressed strong support. 
In June 1992 the General Assembly passed House Bill 3810, which became Public Act 87-1005, which directed LRB to file a compilation of the general Acts of Illinois.  The compilation was filed by LRB, as directed by Public Act 87-1005, on September 14, 1992.  (Alternative sources give the effective date as September 3, 1992.[ citation needed]) The compilation is known as the Illinois Compiled Statutes, or ILCS, and took effect January 1, 1993. 
The previous official reorganizations of the statutes were also revisions in which new acts were passed that superseded existing acts.  Those new acts contained changes to the law that were deemed appropriate.  In contrast, the compilation under Public Act 87-1005 was solely a reorganization; it did not make changes to the text of the law.  The many problems that arose in the course of the 1874 revision, described in pages 25 through 35 of Statutory Revision in Illinois, might have paled in comparison to the difficulties that would have arisen in an attempt to revise nearly 2,000 acts. 
- Decker, John F.; Kopacz, Christopher (2012). Illinois Criminal Law: A Survey of Crimes and Defenses (5th ed.). LexisNexis. § 1.01. ISBN 978-0-7698-5284-3.
- Smith, Lori L.; Barkley, Daniel C.; Cornwall, Daniel C.; Johnson, Eric W.; Malcomb, J. Louise (2003). Tapping State Government Information Sources. Greenwood Publishing Group. p. 126. ISBN 1-57356-387-0. LCCN 2002044846.
- "Organization of the Illinois Compiled Statutes". Illinois Legislative Reference Bureau. Retrieved 10 June 2014.
- Wojcik, Mark E. (2003). Illinois Legal Research. Carolina Academic Press. pp. 78–79. ISBN 0-89089-339-X. LCCN 2003110318. OCLC 52972867.