Congressional enactments are seldom free of ambiguity. In interpreting statutes, the courts and federal agencies often refer to the statutes legislative history to determine the statutes meaning and application.

There are two types of legislative histories. The first follows a bill's progress through Congress. The second relates to the Congressional intent and meaning.

The following two resources can be used to follow a bill's progress through Congress:

• CCH Congressional Index Service (Wirtz Labor Library has this title back to 1939 [79th Congress])
• Thomas (1973 forward [93rd Congress])

To determine the intent of a statute, researchers examine evidence gathered from hearings and reports made by the committee in charge of the legislation and from floor debates found in the Congressional Record. The Congressional Record (1873 to the present)can be located in the Wirtz Labor Library. On WESTLAW and LEXIS you can find the Congressional Record from March 1985 forward.

Additional resources are to the Congressional Hearings since the 104th Congress and to the Congresstional Reports.

Wirtz Labor Library has selected hearings and reports in both paper and fiche on Congress sessions before the 104th Congress. Users have access to both the online catalog and the old print catalog to find the titles that they need. Now the law librarian can scan needed items and send electronic versions of this older information to researchers.

Often the end user doesn't know the exact name of the hearing(s) or report(s) they are looking for. To aid in this part of the research the Wirtz Labor Library has recently purchased a series of indexes that will help the end user identify these items.

Library users can now find information prior to 1970 by using the CIS US Serial Set Index, the US Congressional Committee Hearings Index, the CIS Congressional Committee Prints Index, CIS Index to Unpublished US Senate Committee Hearings and CIS Index to Unpublished US House of Representative Committee Hearings. From 1970 forward the Library has had and will continue to maintain a subscription to the CIS Annual. Since 1984, CIS Annual has included a legislative Hhistory volume detailing all the different items that comprise each public law's legislative history.

Another source of legislative history in the Wirtz Library is the United States Code Congressional and Administrative News often referred to as USCCAN. The Library has this title from 1945 forward. This title reprints the entire law as enacted and includes selected text from Congressional reports.

In addition to these general sources, the Wirtz Labor Library has a number of compiled legislative histories included in the Wirtz Labor Law Library's online catalog.