What is "bluebook"

n. A blank booklet of lined paper used in the administration of examinations, so named because of its pale blue front and back covers.

The Bluebook: A Uniform System of Citation, a style guide, prescribes the most widely used legal citation system in the United States. The Bluebook is compiled by the Harvard Law Review Association, the Columbia Law Review, the University of Pennsylvania Law Review, and the Yale Law Journal. Currently, it is in its 20th edition. It is so named because its cover is blue (see photo).

The Bluebook is taught and used at a majority of U.S. law schools, and is also used in a majority of U.S. federal courts. Alternative legal citation style guides exist, including the Maroonbook and the ALWD Citation Manual. There are also several "house" citation styles used by legal publishers in their works.

The U.S. Supreme Court uses its own unique citation style in its opinions, even though most of the justices and their law clerks obtained their legal education at law schools that use The Bluebook. Furthermore, many state courts have their own citation rules that take precedence over The Bluebook for documents filed with those courts. Some of the local rules are simple modifications to The Bluebook system, such as Maryland's requirement that citations to Maryland cases include a reference to the official Maryland reporter. Delaware's Supreme Court has promulgated rules of citation for unreported cases markedly different from The Bluebook standards, and custom in that state as to the citation format of the Delaware Code also differs from The Bluebook. In other states, notably New York, Texas, and Michigan, the local rules are different from The Bluebook in that they use their own style guides. Attorneys in those states who practice both in federal court and state court must be able to switch seamlessly between citation styles depending upon whether their work product is intended for a federal or state court. Since 2008, California rules of court have allowed citations in Bluebook form as well as the state's own style manual.

An online subscription version of The Bluebook was launched in 2008. A mobile version was launched in 2012 within the rulebook app, an app that allows lawyers, scholars, judges, law students, paralegals, and others involved in the legal profession to reference federal and state court rules, codes, and style manuals on iPad and other mobile devices.