To compile a legislative history for a law, you must first locate the Public Act (P.A.) number for the statute. You can do this by looking at the statute in an annotated code such as:
Check the history note to find a reference to Public Acts (P.A.) number. Note that the first number refers to a General Assembly number, not a year. If you find a reference to "Laws," the session law is pre-1970, and transcripts of debates do not exist.
There are several sources for finding the Public Act as signed into law. The Public Act will also give you the bill number.
You can also search the appropriate General Assembly page to find the correct "Public Act to Bill Number Conversion Table, " resulting in a House (H.R.) or Senate (S.) Bill number.
Full-text transcripts of the floor debates are available on the Illinois General Assembly website from 1971 to the present, organized by legislative day. From 1997-present, the Illinois General Assembly website also provides a report on each bill introduced in the General Assembly, including:
For bill passed before 1997, consult the "Master Index" for both the House and Senate by searching under your General Assembly year and bill number. This Index is found under "Transcripts" and then "Listing" for each chamber.
You can also consult the Legislative Synopsis & Digest (D'Angelo Law, Bookstacks K323z), which prints a chronology of all actions on each bill during the year, available in PDF (1985-2005).
Record the information (including dates of debate, page numbers and action) listed. Note that the second and third readings of a bill are the most likely times for significant debate on a bill.
Search each legislative day and page number individually for debate. Note that transcripts can also be searched by keyword but the OCR for older debates is not always accurate so you risk missing something.