Case Law Research Guide

This guide details how to read a case citation and sets out the print and online sources for finding cases.


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Every law student and practicing attorney must be able to find, read, analyze, and interpret case law. Under the common law principles of stare decisis, a court must follow the decisions in previous cases on the same legal topic. Therefore, finding cases is essential to finding out what the law is on a particular issue.

This guide will show you how to read a case citation and will set out the sources, both print and online, for finding cases. This guide also covers how to use digests, headnotes, and key numbers to find case law, as well as how to find cases through terms and connectors searching.

To find cases using secondary sources, such as legal encyclopedias or legal treatises, see our Secondary Sources Research Guide. For additional strategies to find cases, like using statutory annotations or citators, see our Case Law Research Tutorial. Our tutorial also covers how to update cases using citators (Lexis’ Shepard’s tool and Westlaw’s KeyCite).

Basic Case Citation

A case citation is a reference to where a case (also called a decision or an opinion ) is printed in a book. The citation can also be used to retrieve cases from Westlaw and Lexis. A case citation consists of a volume number, an abbreviation of the title of the book or other item, and a page number. 

The precise format of a case citation depends on a number of factors, including the jurisdiction, court, and type of case. You should review the rest of this section on citing cases (and the relevant rules in The Bluebook) before trying to format a case citation for the first time. See our Bluebook Guide for more information.

The basic format of a case citation is as follows:

Parallel Citations

When the same case is printed in different books, citations to more than one book may be given. These additional citations are known as parallel citations.

Example: 265 U.S. 274, 68 L. Ed. 1016, 44 S. Ct. 565.

This means that the case you would find at page 565 of volume 44 of the Supreme Court Reporter (published by West) will be the same case you find on page 1016 of volume 68 of Lawyers' Edition (published by Lexis), and both will be the same as the opinion you find in the official government version, United States Reports. Although the text of the opinion will be identical, the added editorial material will differ with each publisher.

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Case Law Research Tutorial

Update History

Revised 4/22 (CMC)
Updated 10/22 (MK)
Links 07/2023 (VL)