In many ways, the steps to researching Illinois legislative history is similar to Federal legislative history. Unlike Federal law, where you can often find complied legislative histories, you will probably be starting from scratch with Illinois law.
The Illinois Legislative Reference Bureau has created a guide on how to research the legislative history of a Public Act.
The Illinois General Assembly website (ilga.gov) has:
If you are researching anything before the current General Assembly, use the Previous General Assemblies page.
Westlaw has legislative history documents through the History tab on the top of any statute. Lexis also has search functions for IL Legislative Bill History, IL State Voting Records, and Bill Tracking Reports.
The instructions here are focused on using ilga.gov, a free online resource.
Public Act Number
First, find the statute. Illinois Compiled Statutes are available for free on the IL General Assembly website. You can find a popular names table on Westlaw. West’s Smith-Hurd Illinois Compiled Statutes Annotated is in the library (KFI 1230 1993 .A4–3rd floor Main Stacks). You can also use Westlaw or Lexis.
Use the code section reference to look at the text of the statute, then find the source reference (in parenthesis) to find the Public Act (“PA”) and the date of enactment.
Bill Number
On the ilga.gov Previous General Assemblies site, use the dropdown menu for the year you are looking for. The records go back to 1971-72. Then, click the link to the “Public Act to Bill Number Conversion Table" or "Public Acts by Effective Date". You can use the table to find the number of the bill that became the Public Act.
Indexes to Debates
Go to the home page for the relevant session of the General Assembly and use the “Listing” link next to “Legislation & Laws” to locate the Public Act, and the Bill Number. Click on the Public Act/Bill Number link, and when you get to the bill text, click on Bill Status. Skim the online synopsis of the bill’s passage through the Illinois legislature.
Floor debates in the two chambers of the General Assembly are most likely to occur on those 2d or 3d readings, so make a note of the dates on which those second and third readings of the bill took place in the Senate and in the House? (Remember that a bill is considered in both houses of the legislature.)
Debates
From "Previous General Assemblies," select the relevant Session, and select the House or Senate Transcript you wish to find. Scroll to the relevant Legislative Day and click it to pull up the transcript. You can then browse or do a ctrl-F to search within the transcript for references to your Bill number. The ILGA site does have a search function as well, so you can search the transcripts by key word.
House and Senate Journals.
From "Previous General Assemblies," select the relevant Session and click the link to either House or Senate journals. Use the dropdown menu to find the correct date. Use ctrl-F to search for the bill number. There is also a keyword search option.
For instructions on how to conduct IL legislative history in print, see "Research Legislative History" on our Summer Associate Research Guide.
If you are researching legislative history for a different state, Indiana University has a research guide that covers all 50 states.
From the Illinois Legislative Research Unit