State legislative history materials can be limited. In California, for instance, recordings of hearings and debates from before 2009 can be difficult to find. Still, you can often find some documentation indicating legislative intent. Listed below are some first steps.
Although limited in scope, Westlaw and Lexis both provide some information for bills enacted since the 1990s.
Browse any historical notes, espcecially Revisor's notes added by editors. (For California law, find the relevant statute in both Deering’s and West’s annotated codes.)
If the historical notes don't tell you exactly when the language you care about was added, look up the session laws referred to in the historical notes of an annotated statute. (Use a state-specific guide to legislative history to find out what other information you'll need besides the session law citation.)
Related information for California might be available in: Attorney General Opinions; committee reports and Legislative Counsel commentary; Law Revision Reports; or law review articles.
Finding historical information about a state statute can be tricky. For more help, contact a law librarian or check a state-specific guide like the ones linked here. Also consider visiting the website of the relevant state's law library; many offer customized guidance for locating legislative history information.