This section of the guide is a short introduction to case law research. A more thorough how-to guide on case law is available here.
Should you run into questions or concerns with your research, feel free to reach out to the librarian assigned to your faculty member for specialized advice. Please check this list to determine which librarian you should contact.
Court opinions are published in books called "case reporters." Some but not all court opinions are published. Case law is published in official and unofficial case law reporters, in chronological order. Some opinions, including most trial-level opinions, are unpublished (or "unreported"). However, with the growth of online legal research platforms, you may still be able to locate and read these opinions.
Federal Case Law
Only opinions from the Supreme Court of the United States are officially published. Opinions from the circuit and district courts are still published, but they are found in unofficial (or non-government sponsored) reporters. Like unofficial statutory compilations, the unofficial versions of case law will contain added features that help find other related primary authority. The Bluebook directs you to cite to the official reporter wherever possible.
The official reporter for SCOTUS cases is the United States Reports, abbreviated as "U.S." The Supreme Court Reporter (S. Ct.) and the Lawyers Edition (L.Ed.) are unofficial reporters from West and Lexis that contain the same opinions as the U.S. Reports.
Opinions from the federal Circuit Courts of Appeal can be found in the Federal Reporter, abbreviated as F. (or F.2d or F.3d), published by West.
Opinions from the federal district courts can be found in the Federal Supplement Reporter, or F. Supp., published by West.
Note that while West owns the Federal Reporter and Federal Supplement Reporter, you can still locate and read these cases using Lexis products.
New York State Case Law
Unlike the federal judicial system, New York State has official case reporters for all three levels of court opinion in addition to the West- and Lexis- produced unofficial reporters.
The New York Reports (abbreviated N.Y.) is the official publication for opinions from the New York Court of Appeals, the highest court in New York. The Appellate Division Reports (abbreviated A.D.) is the official publication for opinions from the New York Appellate Division, the intermediate appellate court in New York. The Miscellaneous Reports (abbreviated Misc.) is the official publication for opinions from the trial level courts in New York, including the New York Supreme Courts, Family Courts, Surrogate's Courts, Criminal Court, County Court, and more.
Westlaw also publishes the New York Supplement (N.Y.S.), which contains opinions from all courts in New York.
By Citation
Case citations are the easiest way to retrieve a case. Case citations are structured by volume number, reporter abbreviation, and first page of the case. For example, the citation Brown v. Board of Ed. Topeka, 347 U.S. 483 means that you can find this case on page 483 of the 347th volume of the official Supreme Court reporter. You will be able to find a case by citation even if you only have the unofficial case reporter citation. Common legal abbreviations may be deciphered here or via the Cardiff Index.
Using a Statute
Westlaw and Lexis make it easy to find cases that discuss a statute using the "annotations" included in each database. Annotations refers to the value-added research tools, like lists of citing references, that help collect all information relating to a statute.
If your research begins or brings you to a statute, you can use those annotations to find related case law. Online databases separate case law related to a statute into two different groups: (1) all opinions that cite a statutory section and (2) some specially-selected cases that are particularly useful or helpful for analyzing a statute.
On Westlaw, you can find a list of everything that cites a statute under the Citing References tab. Depending on the statute you are reading, this list has the potential to be quite long and overwhelming. If you want to instead look at a list of cases, broken down by topic, that editors at Westlaw have deemed particularly relevant for the statute, use the Notes of Decisions tab.
On Lexis, you can find a list of everything that cites a statute under the Shepardize this Document tab (it will default to citing decisions). Again, this list has the potential to be long and overwhelming. If you want to look instead at a curated list of cases created by editors at Lexis, scroll down past the text of the statute to the Notes to Decisions section of the page.
Using Secondary Sources
If you are given a research project that looks like it will involve case law, you should consult a secondary source first before jumping into any case law research. Secondary sources will help give some background on the area of law and can also provide some important cases through footnotes and discussion. You can use the search bars on Westlaw or Lexis to search generally for secondary sources using the keywords you generated, or you can select a specific secondary source (like American Jurisprudence) or category of secondary sources (like encyclopedias or treatises) to find useful secondary sources.
A very specific type of secondary source that is useful for case law research is the American Law Reports, or A.L.R. A.L.R. is a compilation of attorney written annotations (articles) that analyze a particular legal issue. These tend to be more in-depth than an encyclopedia article and provide citations to cases on both sides of the issue. You can search for annotations on your topic using the Index volumes at the end of the set of series volumes. Once you have found an annotation on your topic, use the citation given to look up the annotation in the set.
Using Headnotes and Topics
Online databases like Westlaw and Lexis include many tools to help make legal research easier. First, both include headnotes, or brief summaries of the important issues and topics of a case. Headnotes are written and curated by editors at each company and are not the law (and should not be cited as such).
In addition to breaking down the elements of a case, headnotes also help group related case law by topic.
This system on Westlaw is called the Topic & Key Number system. This system breaks the law into over 400 broad topics, which are then further assigned a Key Number for a more specific subtopic. Each headnote on Westlaw is also given a Topic & Key Number that will provide a longer list of cases similar to the one you are reading. Once you select a Topic & Key Number, you can further narrow by jurisdiction, key word, and date. The Topic & Key Number system is a great resource for building your body of case law!
Lexis has a similar system of assigning topics to case law. Under most headnotes, you will see a horizontal list of legal topics in a general to specific order. Just like on Westlaw, you can use these assigned topics to find more cases that discuss a particular relevant topic.
Just like with statutes, a researcher must check that their case law is still "good law." Researchers use a tool called a citator to track later authorities citing primary law to determine its precedential value. When updating case law, you are looking for subsequent opinions and statutes that may have invalidated or questioned your case. You can also use a citator to look for subsequent case law affirming the precedential value of your case.
The online citators use color-coded signals to let the reader know the status of the case. A red signal usually means the case is no longer good law. A yellow signal usually means there is some negative treatment. Because citators are not primary authority and are created by databases, you should not take the signal at face value. If you see a red flag on a case, you must read that case to determine (1) what the jurisdiction is and (2) what the red flag refers to before determining if the case is detrimental to your argument. Negative treatment includes negative treatment of a case in subsequent case law and pending or enacted legislation.
Westlaw's citator is called Key Cite; Bloomberg's is called BCite. Lexis's is called Shepard's (you might hear people refer to updating caselaw as "shepardizing" the case law - the term has taken on the meaning of a citator, kind of like calling all tissues a Kleenex).
Updating on Westlaw
If a case has negative treatment, you will see a red or yellow flag at the top of the case. Click the signal; negative treatment will be displayed first.
Updating on Lexis
If a case has negative treatment, you will see a red or yellow icon at the top of the case. You can also click the "Shepardize" button on the right side of the screen. You will see a list of all authorities citing the case and use the filters and tabs to check for negative history or treatment.
Once you have found, read, and updated a relevant case, you can expand your research in the following ways: