There is usually an index to each legislative session, but to find a session law using the annual or biennial index, a researcher would have to know the legislative session during which a law was enacted. Luckily, code volumes usually contain references to the session law or laws that have been incorporated in a particular code section. This makes it much easier to find a session law. Session laws are sometimes published in legislative advance services. These pamphlets are used to find additions or amendments made since the latest pocket parts were prepared for the code volumes.
Session laws are the most authoritative form of the law.
If a difference in the wording of a statute occurs in its code form and its session law form, the words of the session law are controlling. Session laws are used in historical research, in compiling legislative histories, and are cited as proof of the historical fact of enactment, amendment, and repeal. They are also useful in determining which laws were in force at a particular time. The Boston College Law Library has the session laws of the fifty states as well as all federal session laws. The official set of federal session laws, Statutes at Large , is at Law General Collection KF 50.