First, determine whether someone else has already compiled and published a legislative history on the statute you are researching. The first question to ask yourself: Has someone done the work for you? Many legislative histories have been compiled, so if you need a legislative history for a major statute, look first to see if you can find a complete one before assembling one yourself.
There are a number of free sources:
Law Librarian's Society of Washington DC has a list of compiled legislative histories for selected U.S. laws available on the internet. Search by popular name or Public Law number.
Library of Congress (LOC) has compiled legislative histories in individual monographs (a monograph is a detailed written study of a single specialized subject). Use the linked "Advanced Search," and search the term "legislative history" AND the popular name or public law number of the relevant statute.
If you are not sure of the public law number you can browse the Library of Congress catalog. From the drop-down menu, select "SUBJECTS containing" as your browsing option, and then type keywords AND "legislative history" into the Search box.
Individual agencies often publish legislative histories for major statutes under their jurisdiction. Examples.
ProQuest Legislative Insight contains legislative histories primarily from 1929 to the present, with a smaller number of histories dating back to 1836.
LexisNexis has CIS Legislative Histories from 1970 through current (abstracted documents only) in the file LEGIS;CISLH. LexisNexis has selectively compiled legislative histories available. One can retrieve a CIS Legislative History document by first retrieving a Public Law, by citation, and then clicking on the CIS Legislative History link under the "Text" section.
Westlaw has access to legislative history materials in a number of formats. You can search US GAO Federal Legislative Histories (FED-LH), which include comprehensive legislative histories for most U.S. Public Laws enacted from 1921 to 1995 (rolling release), as compiled by the U.S. Government Accountability Office, including the text of laws, bills, committee reports, Congressional Record documents, transcripts of hearings, and other documents in PDF format. If you are looking at a statute, there is a link at the top of the page related to hearings and reports - "History." Westlaw also offers the Arnold & Porter Collection of legislative histories, located by clicking on "Content Types" --> scrolling down to "Specialty areas" --> clicking on "Legislative History" --> looking to the right side of the page towards "Tools & Resources" --> and clicking on "Arnold & Porter Legislative Histories."
ProQuest Congressional offers compiled legislative histories for all federal acts since the 91st Congress (1969-1970), with links to the full-text of many of the legislative documents. This service also offers indexing for pre-1970 legislative documents. If a compiled legislative history is not available on Proquest Legislative Insight, the documents may still be available in Proquest Congressional.
HeinOnline has selected legislative histories available in a full-text, fully searchable format. Click on the U.S. Federal Legislative History Library.
US Code Congressional and Administrative News (USCCAN) is also available on Westlaw (database: USCCAN). From 1948-1989, the database is the same as the print version of USCCAN. From 1990, the database contains the full text of all congressional committee reports, including reports on bills that did not become law.
To quickly locate the most important history documents for legislative acts from 1943 through the current Congress, look in:
US Code Congressional and Administrative News (USCCAN)
LAW FEDERAL 1st floor KF 48 .U552 (available in Westlaw)
Sources of Compiled Legislative Histories, by Nancy P. Johnson
LAW STACKS 2nd floor KF 42.2 2014 (available on HeinOnline)
HeinOnline includes links to selected full-text documents. From the home page, click on "U.S. Federal Legislative History Library," then click on "Sources of Compiled Legislative History Database."
Federal Legislative Histories: An Annotated Bibliography and Index to Officially Published Sources, by Bernard Reams
LAW REFERENCE 2nd floor KF 42.2 1994
CIS Annual 1970 - present
LAW MICROFORMS 1st floor KF 49 .C62
This print index includes complete legislative histories with references to the full-text documents available in the Library's CIS microfiche collection. Please see a Reference Librarian if you need help using the index. From the 91st to 98th Congresses (1970 - 1983) legislative histories are found at the end of the Abstracts volume. Beginning in 1984, an Annual Legislative History volume lists histories by public law number. Each history contains an abstract of the public law and full bibliographic citations to relevant documents.
The William A. Wise Law Library also has legislative histories in print and on microfiche. Use the Wise Law Library Online Library Catalog at http://lawlibrary.colorado.edu/?q=find&qt-find_search=1#qt-find_search.
[Hint: Use the "keywords" search option to search for keywords from the title of the act (example: searching "american disabilities legislative" will bring up the call number for a book containing the full text of all the legislative history documents relating to the Americans with Disabilities Act)]