When Congress passes an act and it is signed into law, the language of the text may be ambiguous. There may be multiple ways to read the text and apply it to specific situations. As these circumstances arise, judges must seek to interpret the law so that it makes sense. One way is to look to the exact language of the statute, and apply it as best as possible. Many judges look to the legislative history, that is the path the law took to enactment and the documents that were created along the way, as a way of discerning the intent of Congress in passing the act.
There is a fairly standard set of documents produced along the way. The typical legislative history will include bills, including the text of competing bills, and the text of amendments; committee reports, including those of several committees that may review the language of a bill; hearings held by committees; debate on the floor of the House and Senate; and messages by the President upon signature.
These various documents have different impact on a court. As a general rule, reports usually have the most weight as they represent the most detailed and documented statement on the measure. Hearings have less weight, as the statements made by witnesses are the opinions of those witnesses rather than statements of rationale by lawmakers. Debates carry weight depending on who is making the statement. Statements from sponsors, the authors of the legislation, the floor managers, and others closely connected with the legislation have more weight than lawmakers who merely support or oppose the measure. Competing and/or failed bills may also give some insight as to what Congress meant by analyzing what they didn’t enact. However, there are usually political reasons behind what is enacted, which is not necessarily a statement of the intent of Congress.
What follows is a more detailed examination of these items, and sources for them.