Types of Secondary Sources
Primary sources have documents that are "the law." The documents are created by bodies with legal authority. For example, cases are decided by courts; statutes are enacted by legislatures; regulations are issued by administrative agencies.
Secondary sources are all the materials that are about the law. They are written by lawyers, law professors, law students, independent authors, and publishers' staff writers. They are useful in understanding the law, but they are not the law. You can't go to jail for disobeying a treatise or failing to comply with a dictionary!
Law has many types of secondary sources, used for different purposes:
- Casebooks are collections of edited cases and other materials used to explore different issues in classes. They are generally not used in research.
- Study aids (including Hornbooks, outlines, and Nutshells) are used to get an overview of a topic. They are meant to complement what is covered in a class. See Study Aids for Law Students.
- Treatises (often many volumes) cover areas in depth. They are used to learn a lot about an area. Often researchers use tables of contents, indexes, or online searches to find a short section that covers a narrow question.
- Dictionaries define legal terms.
- Legal encyclopedias attempt to cover all of U.S. law. They are used to get an overview of a field or to find general rules of law. They are heavily footnoted and so can be tools for finding cases.
- Law reviews and other legal periodicals publish articles with scholarly analysis of legal issues.
- American Law Reports (A.L.R.) publishes articles called "annotations" that summarize cases from around the U.S. on specific topics.
- Practice materials (including form books and various deskbooks and guides) offer practical guidance.
A law library also includes many of the sort of "regular books" you might see in a bookstore or public library, such as works of journalism, history, or political commentary.
Discussions of legal issues are also found in blogs, law firm and government websites, and even Twitter, and so these newer media are secondary sources as well (although this guide doesn't cover them).
Photo credit: U.S. Supreme Court building from https://www.supremecourt.gov/.
Why Use Secondary Sources?
It is often useful to start your research by finding an on-point secondary source, especially for an unfamiliar area of law. But why? Why not just start searching for relevant cases or statutes? Well, as explained by Kent C. Olson in Legal Research in a Nutshell (13th ed. p. 25),
Primary sources such as statutes and cases can be confusing, ambiguously worded documents. Secondary sources are usually more straightforward and try to explain the law. They summarize the basic rules and the leading authorities and place them in context, allowing you to select the most promising primary sources to pursue.
In other words, starting with a secondary source is more efficient and will provide you with an understanding of the forest AND help you identify the most important individual trees.
If you would like additional instruction on secondary sources, check out this lesson on CALI (visit the law student restricted databases page if you need the CALI authorization code):
- Introduction to Secondary Sources (CALI Lesson)This lesson will provide an overview of secondary resources used in legal research. Secondary resources are books and other material ABOUT legal subjects and issues: they discuss and explain primary resources such as cases and statutes and can be useful in assisting our understanding about specific areas of law. The student will learn about the different types of secondary resources and what secondary resources are most useful for specific types of legal research tasks.
Related Gallagher Guides
- Study Aids for Law Students [Gallagher Law Library]Books and other materials related to law school classes and law school success.
- Washington Practice MaterialsDeskbooks, Washington Practice, court rules, etc.
- Legal Dictionaries [Gallagher Law Library]U.S. legal dictionaries (general and specialized), historical dictionaries (want to know how dictionaries defined your term when a statute was drafted?), bilingual and multilingual legal dictionaries.