A legislative history refers to the documentation created during the (Congressional) legislative process, from the introduction of a bill into either the House or Senate, through the various steps before it either becomes a law, is vetoed, or just dies in session. The majority of bills do not become law. However, the documentation each bill generates may contribute useful background material when researching a similar bill that does become law.
A legislative history can help interpret a statute, especially where the statutory language is vague or unclear. The history of a statute can help clarify the law and assist in determining how it applies to a specific situation, but is never binding upon a court. A history conducted on the background of the statute provides insight into the meaning and intent of the legislative body that created the law.
Remember, too, that the effect of legislation is modified by actions in other branches of the federal government. Through the Judicial branch, court decisions affect law and how it is applied, and through the Executive branch, agency rules and regulations can both influence the implementation of statutory law and generate regulatory law. The actions of both of those branches of the government must be considered when doing a complete background of statutes.
In conducting a legislative history, you begin with clues (popular names, bills, Public Law numbers, etc.) that lead you to other information. Do not expect to obtain all answers to your research from a single source. Be flexible. Be patient. Be diligent.
Good luck, and please ask a librarian for help any time you need it!
For information on how to cite government documents, use the Bluebook: A Uniform System of Citation:
The Bluebook
University of Michigan-Flint