Legislative history (1844) The proceedings leading to the enactment of a statute, including hearings, committee reports, and floor debates. Legislative history is sometimes recorded so that it can later be used to aid in or influence interpretations of the statute. Black's Law Dictionary (10th ed. 2014), legislative history. Bryan A. Garner, Editor in Chief.
In other words, it is finding and reading the government background information contained in Congressional documents that informs one about the creation of a bill, an act, or a law.