A case citation is the standardized notation for referencing a written judicial decision in a legal action. It enables people to efficiently locate a published version of the case decision when needed. Every country has a different system for citing cases, and some have more than one competing format, but most citation systems use some combination of the name of the case, the court where the case was decided, the year decided, the name of the periodical where the case was published, and the page number where the case can be found in the publication.
Judicial case law is the foundation of legal systems based on English common law. The legal doctrine behind the importance of case law is the requirement that judges comply with past precedent when deciding current cases. Precedent mandates that a judge treat a prior decision on the same facts as currently presented as binding. A judge in this system of law cannot simply come to a different decision when presented with facts that have already been adjudicated. Before a judge can rely on past case law, however, there has to be a system to locate and refer to those past decisions.
Courts typically publish important written decisions by judges in books called reporters. In the U.S., circuit and appellate courts at the federal level have a reporter, and the U.S. Supreme Court has its own reporter. Cases that are important benchmarks for establishing precedent are selected for publishing in the appropriate reporter. When a person needs to reference a case, he lists the abbreviated name of the case, the court that decided the case, the year decided, the reporter where it can be found, and the page number. The case citation works much like a footnote and enables a person to locate source material.
Case citation has been largely standardized in the U.S., regardless of the court system involved. Certain law schools have worked to establish a style guide called the Bluebook that provides the authoritative format for all legal citations. Law students are trained in the use of the Bluebook, and have promulgated this style as they have entered the workforce. Other countries, however, have had varying degrees of success in standardizing their legal reference system.
Another important factor in the use of case citations, particularly in the U.S., is the continuing development of proprietary online databases that have digitized case law so cases can be downloaded from the Internet. Private companies that have developed these databases have also promoted a system of parallel citations. A parallel case citation refers a person to the location of a case in the electronic database rather than in the reporter.