Secondary Sources

Secondary Sources in the United States

Using Secondary Sources

Although primary sources of law (i.e. case law, statutes, and constitutional provisions) are the sources that establish the law on a given topic, they are often tricky places in which to locate answers. Secondary sources (sources that tell you something about the law), often explain legal principles more thoroughly than a single case or statute, and using them can help you save time. Secondary sources help you avoid unnecessary research since you’re tapping into work that someone else has already done on an issue. Moreover, they are useful for learning the basics of a particular area of law, understanding key terms of art in that topic, and identifying essential cases and statutes for that issue. Secondary sources include Legal Encyclopedias, American Law Reports (ALR), Treatises, and Law Review articles. This legal Encyclopedia provides a basic overview of these sources as well as information about finding, citing and using these materials in the United States.

Secondary Sources in Legal Research

“Knowledge of secondary sources, their authority, their role in the research process, and how they function is an important component in the legal research process. “Secondary sources are usually more straightforward and try to explain the law.” (1) For inexperienced researchers, secondary sources can provide much needed background, explanation, and grounding in the law. Secondary sources can help a researcher achieve greater understanding about how the law works, discover idiosyncrasies or peculiarities in a particular area of law, discover exceptions to or modifications of the law, and gain insight into how the law in question is applied practically. For these reasons, secondary sources are often recommended as the starting place for legal research.”(2) (3)

“(O)nce researchers comprehend the shortcuts and explanations that secondary sources can offer, they will seek out secondary sources when embarking on new research projects in order to save time. Thus, cultivating and reinforcing an understanding of such sources can be quite valuable.” (4)

US Secondary Legal Resources

This section discusses the following American secondary legal resources: textbooks, legal journals, encylopedias and case law digests.


A good starting point for legal research can often be to check textbooks on your topic. In the United States, many lawyers, judges and academics write books on a variety of legal topics. Some of the leading publishers of legal treatises in the U.S. include West Publishing, Lawyers Co-operative Publishing, CCH, Matthew Bender, and Oceana Publications. Consider doing a keyword search using, for example, the library catalogue to identify titles of textbooks on your topic. If you find a title on point, check the table of contents or index of the book to see if there is any discussion of your legal problem.


In relation to textbooks, some of the most important and persuasive commentaries on American law are found in the series of Restatements prepared under the auspices of the American Law Institute and published by West. The original intention of the A.L.I. was to provide “an orderly restatement of the general common law of the United States,” and many of the important fields are covered. These include contracts, torts, agency, trusts, conflict of laws, judgments, property, security, and restitution.

The Restatements are written by judges, lawyers, and academics in a collaborative process that produces many tentative drafts, which are widely distributed and are of considerable interest to scholars and researchers. (The Restatement, Second of the Law of Contracts was completed over a seventeen year period, during which fourteen tentative drafts were published.) The original Restatements have been almost completely replaced by the Restatements, Second and in some cases further numbered revisions .

Each Restatement is organized by chapters covering a particular subject, subdivided into topics that contain one or more black letter statements of the law. Each statement is followed by an explanatory comment o n the general principles, the relationship of the statement to previous Restatements, and illustrations of the proposition by moot examples. The reporter’s note refers to other sections and cites case authorities.

Legal Journals

Law journals are a good source of information since academics, lawyers or other experts in their field usually write the journal articles. An easy way to find relevant journal articles is to search an index of legal periodicals, which usually allows you to search by subject, author or title. By searching various legal periodical indexes, you can find citations to full-text articles, case comments and book reviews. A relevant full-text journal article can in turn lead you to other significant sources included in its bibliography and footnotes. The Law Library website has a link devoted to finding law-related journals.

There are two major sources in electronic format for searching for law-related journal articles: the Index to Legal Periodicals & Books and Legal Trac, by subscription.

Index to Legal Periodicals and Books

The Index to Legal Periodicals and Books is an American periodical index that covers journals from the U.S., Canada, Great Britain, Ireland, Australia, and New Zealand. It dates back to the nineteenth century, and contains the following indexes: Subject and Author; Cases; Statutes; and Book Reviews. It is published in annual volumes that are cumulated every three years. The version available on the Internet (by subscription) is easy to use. The software allows you to print, download or e-mail your search results. To search for articles, simply type in keywords or search by author or title. Another useful feature of the web version is the “Index” button that allows you to see a list of every keyword used in the index. From the list, you can select those words you wish to use in your search.

Legal Trac

This is an American periodical index which covers journals from the U.S., Canada, the U.K, Ireland, Australia, and New Zealand. This Index only goes back to 1980, but it is now available through an Internet subscription. The online version is updated regularly and allows for a variety of search options. Instructions are found on-line and are easy to understand.

Shepard’s Law Review Citations

Shepard’s Law Review Citations is an indispensable tool when using American periodical literature. It provides citations to articles published in law reviews and legal periodicals since 1957 referred to by the United States Supreme Court, lower federal courts, state courts and other articles in law reviews. It consists of two volumes: a bound volume and a cumulative supplement. To “note up” a particular journal article, turn to the bound volume of Shepard’s Law Review Citations . Articles are indexed under the journal that it appeared in (in bold letters at the top of the page), the volume number of the journal (in large bold letters), and the page number on which the article begins (in small bold letters between dashes). Citations to cases in which the article was cited are listed, followed by a list of citations of other articles in which the case was referred to. To decode the abbreviations, consult the list of abbreviations at the front of the volume. You should also refer to the paper-bound supplement for the most recent information.

Legal Encyclopedias

Legal encyclopedias are a useful starting point for research. They provide a good overview of the law by organizing the law into manageable topics, and they include references to applicable primary sources of law.

Corpus Juris Secundum

The Corpus Juris Secundum (C.J.S.), published by West, is an encyclopedia which can give you general background knowledge of an area of law and can refer you to specific cases. Key numbers accompanying every paragraph in the C.J.S. direct researchers to corresponding sections of West’s American Digests series.

Always update your C.J.S. research by consulting the annual “pocket part” in the back of the main volume. Updated information is indexed to correspond with the paragraph and page numbers of the main work.

Words and Phrases Defined

The Words and Phrases volumes are a companion to the Corpus Juris Secundum legal encyclopedia. The series purports to locate all cases that have ever offered judicial definition of a word or phrase. Extensive cross-references are provided. Since each paragraph is supported by at least one authority, reference to the West report of the supporting case will provide the relevant key number, with which all other cases on the same point of law can be found through the American Digest.

Case Law Digests or Summaries

Another useful tool for finding relevant court cases are case law digests or summaries. Various publishers compile digests of cases by topic and prepare short descriptive summaries of each case, along with a citation to the full-text of the case. In the United States, the leading case law digest service is published by West as part of their American Digests series.

The American Digests Series

West’s system of key number digests probably constitutes the most comprehensive subject index of case law ever undertaken. The system divides the entire field of American law into seven main top headings, thirty-two sub-headings, and over four hundred topics. Each topic is further divided into sub-topics, which are identified by individual “key” numbers.

West takes every case it publishes, identifies every point of law contained in it, and writes a one-sentence headnote for each point. Each headnote is numbered, and the same number is printed in the reported decision at the paragraph at which the point of law is discussed. Each headnote is also labeled with the digest key number that identifies its substance.

West’s Digests bring together all the headnotes bearing the same key number. West publishes several Digests , each of which gathers headnotes from a different geographical or jurisdictional source. The American Digest series covers all the decisions published in all of West’s Reporters, and is therefore the master index to all of U.S. case law.

Volumes of the American Digest are issued regularly in a series called the General Digest. Each new volume, several of which are issued per year, publishes the headnotes written in any of West’s reporters since the last volume. Every five years the General Digest is consolidated (it used be to consolidated every ten years, hence the title). The consolidated volumes are called Decennial Digests.


Notes and References

1. Morris L. Cohen & Kent C. Olson, Legal Research in a Nutshell 32 (10th ed. 2010). Note by the author of the Law Journal article.

2. Ronald E. Wheeler Jr., Does WestlawNexr Really Change Everything?, The Implications of WestlawNext on Legal Research Ronald E. Wheeler Jr. 363 Law Library Journal, Vol. 103:3 [2011-23]

3. See, e.g., Morris L. Cohen & Kent C. Olson, Legal Research in a Nutshell 32 (10th ed. 2010) and Nancy P. Johnson, Best Practices: What First-Year Law Students Should Learn in a Legal Research Class, 93 Legal Reference Services Q. 77, 80 (2009) (“For students to relate to legal research, they must know how and when to use the materials”). Note by the author of the Law Journal article.

4. Ronald E. Wheeler Jr., Does WestlawNexr Really Change Everything?, The Implications of WestlawNext on Legal Research Ronald E. Wheeler Jr. 363 Law Library Journal, Vol. 103:3 [2011-23]

Further Reading

Nancy P. Johnson, Robert C. Berring & Thomas A. Woxland, Winning Research Skills
117 (4th ed. 1999).

See Also

  • Primary vs. Secondary Authority
  • International legal sources of information
  • Legal Research Guides
  • International law sources
  • Free internet US legal research



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