case law research guide

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Legal Research: A Guide to Case Law

Introduction.

• Federal Court Decisions
• State Court Decisions
• Decisions by Topic (Digests)
• Databases and Online Resources
• Dockets and Court Filings

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Authors: Emily Carr, Senior Legal Reference Librarian, Law Library of Congress

Elizabeth Osborne, Senior Legal Reference Librarian, Law Library of Congress

Editors: Barbara Bavis, Bibliographic and Research Instruction Librarian, Law Library of Congress

Anna Price, Legal Reference Librarian, Law Library of Congress

Note: This guide is adapted from a research guide originally published on the Law Library's website .

Created: September 9, 2019

Last Updated: September 23, 2024

Each branch of government produces a different type of law. Case law is the body of law developed from judicial opinions or decisions over time (whereas statutory law comes from legislative bodies and administrative law comes from executive bodies). This guide introduces beginner legal researchers to resources for finding judicial decisions in case law resources. Coverage includes brief explanations of the court systems in the United States; federal and state case law reporters; basic Bluebook citation style for court decisions; digests; and online access to court decisions.

Court Systems and Decisions

The United States has parallel court systems, one at the federal level, and another at the state level. Both systems are divided into trial courts and appellate courts. Generally, trial courts determine the relevant facts of a dispute and apply law to these facts, while appellate courts review trial court decisions to ensure the law was applied correctly.

Stare Decisis (Precedent)

In Latin, stare decisis means "to stand by things decided." In the U.S. legal system, this Latin phrase represents the "doctrine of precedent, under which a court must follow earlier decisions when the same points arise again in litigation." ( Black's Law Dictionary , 11th ed.) Typically, a court will deviate from precedent only if there is a compelling reason. Under "vertical" stare decisis , the decisions of the highest court in a jurisdiction create mandatory precedent that must be followed by lower courts in that jurisdiction. For example, the U.S. Supreme Court creates binding precedent that all other federal courts must follow (and that all state courts must follow on questions of constitutional interpretation). Similarly, the highest court in a state creates mandatory precedent for the lower state courts below it. Intermediate appellate courts (such as the federal circuit courts of appeal) create mandatory precedent for the courts below them. A related concept is "horizontal" stare decisis , whereby a court applies its own prior decisions to similar facts before it in the future.

Case Law Reporters

Decisions are published in serial print publications called “reporters,” and are also published electronically. Reporters are discussed in greater detail under " Federal Court Decisions " and " State Court Decisions ." Information about how to cite decisions in a reporter is discussed under " Citations ."

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• Last Updated: Sep 23, 2024 2:12 PM
• URL: https://guides.loc.gov/case-law

Basic Legal Research Guide: Case Law

• Getting Started
• Dictionaries
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• Law Reviews
• Restatements
• Statutes and Codes
• Administrative Law
• Illinois Resources
• Research Strategy

Accessing Cases in Print

Please note that the Law Library is no longer updating any state law reporters in print. The Law Library is retaining reporters from states besides Illinois on the 5th floor of the Library. Regional reporters and digests are located from call numbers KF 35 .A7 ( Atlantic Reporter ) through KF 135.S8 ( Southern Reporter ); state reporters and digests (if we own them) can be found with the non-Illinois state law materials (call numbers KFA through KFW ). See the map below for the location of the regional reporters and digests and state reporters in relation to the stairwell.

Federal case law reporters and the Federal Practice Digest are still being updated in print; all sets can be found on the 4th floor of the Law Library. See the map below for their location in relation to the stairwell.

About the National Reporter System

Cases are published in chronological order based on the date they were decided, and not by subject. Unfortunately, however, the research projects you receive usually will be asking you to research a legal issue (i.e., a subject). Therefore, you need an index to the reporter system. This is where the West American Digest System  and the  Topic and Key Number system come in handy. West publishes unofficial reporters as part of its National Reporter System  with the goal of including every reported case from every jurisdiction. For state cases, West publishes seven regional reporters, which each include cases from several states. West publishes a map that shows which states are covered in each regional reporter. Note that these do not always make geographic sense; for instance, Oklahoma and Kansas are listed as "Pacific" states.

About the West Key Number System

• Searching with Key Numbers in Westlaw Edge - Quick Reference Guide

Cases are published in chronological order based on the date they were decided and not by subject. However, the research projects you receive usually will be asking you to research a legal issue (i.e., a subject). Therefore, you need an index to the reporter system. The West Key Number System  provides an indexing function for all published cases, enabling a researcher to locate cases by subject from any court in any jurisdiction. The system also acts as an abstracting service, providing researchers with short summaries of the points of law discussed in the indexed opinions. 

The Key Number System subdivides the law into over 450 broad legal  Topics , which are then further subdivided into Key Numbers , which are assigned to specific legal issues within the broader Topics. Topics and Key Numbers are consistent throughout West's System; the same subject arrangement is applied to all cases from every jurisdiction, so that if you find a case from one jurisdiction that discusses a legal issue you are researching, you can use the Topic and Key Number for that issue to find other cases from other jurisdictions that discuss the same issue. The "Searching with Key Numbers" guide (above) provides more detail.

West employs attorneys who read each case, identify the point(s) of law discussed, summarize the point(s) of law in a headnote (a paragraph summary of the point of law) using consistent legal terminology. At least one Topic and Key Number are assigned to each headnote. These headnotes will appear in a West  digest under the appropriate Topic and Key Number and at the beginning of each case as it appears in a West reporter. 

Therefore, headnotes act as the bridge between the Key Number System and cases: you can use the headnotes from a case you've identified and look for similar cases on the same topic. Alternatively, you can start with the Key Number System, look up your subject by Topic and Key Number, and then find cases by reviewing the language of the headnotes you find.

About Cases

Cases are opinions written by judges that resolve disputed legal issues (as opposed to disputed factual issues ). Researching cases is important because of the doctrine of stare decisis  or precedent . Under the principle of stare decisis , courts are bound to follow the rulings of law from previously decided cases in the same jurisdiction when facing similar cases currently before the court. For the legal researcher, reviewing cases from a court will help determine how the court will rule if given a similar factual situation. In the U.S. system, the only published cases you will find are from intermediate appellate courts and supreme courts. Most trial court decisions are not published.

Cases are published in chronological order in reporters . There are two different categories of reporters that you need to know:  official reporters , which are usually published by a government entity, and unofficial reporters , which are published commercially (usually by either West or Lexis). 

To find a case in a reporter, you will need to know its citation . A case citation includes the name of the case, the volume number of the reporter containing the case, the abbreviation for the reporter, the first page of the case, and the year of the decision. For example:

P.G.A. v. Martin , 532 U.S. 661 (2001).

To find the text of this case in print, you would go to volume 532 of the United States Reports (the official reporter of the U.S. Supreme Court) , then page 661. The U.S. Supreme Court decided the case in the year 2001. To find it online, you would search by the citation.

You will often see multiple citations to the same case when the case is reported in multiple reporters (called  parallel citations ).  Table T.1  of  The Bluebook  lists the reporters (both official and unofficial) for every jurisdiction in the United States. For example, the P.G.A. v. Martin  case below is reported in three reporters in the following order: the United States Reports (the official reporter of the U.S. Supreme Court),  the  Supreme Court Reporter   (West's unofficial reporter), and the  Lawyers' Edition   (Lexis's unofficial reporter).  

P.G.A. v. Martin , 532 U.S. 661, 121 S.Ct. 1879, 149 L. Ed. 2d 904 (2001).

How to Read a Case

At the top of the reporter page (see below), you will see the citation to the case, including any parallel citations (citations to the same case in other reporters). Then you will see a short summary of the case (the syllabus ), which includes an indication of how it got to the court that has issued the opinion, and the holding(s) on the point(s) of law. After the syllabus, you will see the headnotes discussing the point(s) of law in the case in the order in which they appear in the opinion, as well as the Topics and Key Numbers that can be used to find other cases on the same legal issue(s). Next is the actual text of the opinion.

One important note: The headnotes and summary are NOT written by the court; they are written by West editors. Therefore, you should never cite to a case based on what you've read in the syllabus and headnotes; you must read the case and cite to the language written by the court.

For additional insights, Prof. Orin Kerr's article " How to Read a Legal Opinion: a Guide for New Law Students " explains what judicial opinions are, how they are structured, and what to look for when reading them.

Using Citators

Citators  perform three functions for legal researchers. A citator will tell you if the case you've found is still "good law," or if subsequent decisions have weakened its authority or overruled it altogether. A citator can also provide citations to other cases and secondary sources that discuss the same legal issue as in the case you've found. Finally, a citator can provide you with case history (references to other proceedings in the same case).

Each subscription research service has its own citator. In Lexis, the citator is called Shepard's . Westlaw's citator is called KeyCite . Bloomberg Law's citator is called BCite . The following presentations will show you how each citator works. Westlaw also has a "Quick Reference Guide" (PDF) for using KeyCite (see below).

If you have access to multiple citators, it's a good idea to check your case in each citator, because citator results will often include different cases, different secondary sources, and different interpretations of subsequent cases that have cited to your case.

Lawyer's Nightmare: DOL Blames Westlaw for Skimpy Brief - this Law360 article demonstrates the hazards of relying on the results of just one research platform/citator.

Below are vendor-produced materials on citators: a PDF Guide to using KeyCite in Westlaw, and video tutorials on using Shepard's in Lexis and BCite in Bloomberg Law.

• Checking Cases in KeyCite - Quick Reference Guide

BCite from Bloomberg Law - Law School Team on Vimeo .

Subject Guide

CALI LibTour - West's Digests

As part of its LibTour podcast series, CALI created this brief introduction to the West American Digest System . Follow the link below to the podcast.

• CALI LibTour Podcast - West's Digests

How to Cite Cases - Examples

Rule B10 (Bluepages) of The Bluebook (21st edition) covers how to cite cases in non-academic legal documents.  The Bluebook , however, notes that practitioners should be aware of local court rules and specifies on p. 3,"Make sure to abide by any citation requirements of the court to which you are submitting your documents."  Table BT2 of the Bluepages contains an index of jurisdiction-specific citation rules. See the " Illinois Resources " tab of this guide for specific information on citing cases, statutes, and regulations in Illinois court documents.

There are many variables involved in citing cases, so you will probably have to check one of the sub-parts of a rule to determine how to cite your particular case. The following example is the first one included in rule B10 (rule B10.1) (Bluepages) (see p. 11)

Engel v. Vitale , 370 U.S. 421, 430 (1962) ("The Establishment Clause, unlike the Free Exercise Clause, does not depend upon any showing of direct governmental compulsion . . . .").

The components of the citation are, in order: the name of the case; the published or unpublished source in which the case can be found; a parenthetical indicating the court and year of decision; other parenthetical information, if any; the case's subsequent history, if any. For the case name, omit all parties other than the first party listed on each side of the "v." per rule B10.1.1 (Bluepages) . In the above citation, note that the first page of the case is listed, as well as the specific page referred to (pinpoint citation) per rule B10.1.2 (Bluepages) . Per rule B10.1.3 (Bluepages) , when citing decisions of the U.S. Supreme Court, or a state's highest court, do not include the name of the deciding court, as in the above example.

Table T6  (p. 304) lists abbreviations for case names and institutional authors in citations.

This example for a federal appellate court case is listed in rule B10.1.3 (Bluepages) (see p. 13):

Envtl. Def. Fund v. EPA , 465 F.2d 528, 533 (D.C. Cir. 1972).

The Bluebook  notes that the Bluepages retain the tradition of underlining certain text, although italics are equivalent (see p. 6).

Rule 10 (Whitepages) (see p. 95) contains the rules for citing cases in academic works. Some examples The Bluebook provides are:

Meritor Sav. Bank v. Vinson, 477 U.S. 57, 60 (1986).

In this example, the case was published in volume 477 of the U.S. Reports (the official reporter of the U.S. Supreme  Court). The case starts on p. 57, but the cited information appears on p. 60. The case was decided in 1986.

Ward v. Reddy, 727 F. Supp. 1407, 1412 (D. Mass 1990). 

In this example, the case was published in volume 727 of the Federal Supplement (a West reporter that contains selected decisions of the U.S. District Courts). The case starts on p. 1407, and the cited information appears on p. 1412. The case was decided by the District Court of Massachusetts in 1990. 

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Library electronic resources outage May 29th and 30th

Between 9:00 PM EST on Saturday, May 29th and 9:00 PM EST on Sunday, May 30th users will not be able to access resources through the Law Library’s Catalog, the Law Library’s Database List, the Law Library’s Frequently Used Databases List, or the Law Library’s Research Guides. Users can still access databases that require an individual user account (ex. Westlaw, LexisNexis, and Bloomberg Law), or databases listed on the Main Library’s A-Z Database List.

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Case Law Research Guide

• Online Resources for Cases
• Introduction
• Print Case Reporters
• Finding Cases: Digests, Headnotes, and Key Numbers
• Finding Cases: Terms & Connectors Searching

Key to Icons

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• On Bloomberg
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• Preeminent Treatise

Online Federal Case Law by Court

For free and low cost resources, please consult our Free Sources of Case Law Resarch Guide.

Published Federal Case Law

Special Courts & Topical Case Sources

Special courts have original jurisdiction over specific subject matter, or were established by Congress under Article I of the Constitution (e.g. the United States Tax Court). Topical reporters include specific types of case case law published in specialty reporters. This list of federal primary sources provides links to the Law Library catalog record for a publication's print edition and access to the publication's digital formats for Law Library patrons.

Check the topical research guides for treatises and secondary sources on tax law ( research and treatise guides), bankruptcy law , international trade law , customs law , military law , and tribal law . For more subject specific case reporters, check the individual topical research guides .

State Case Law

For publications of state case law sources, see our State Legal Research guide and our individual  state research guides . 

Free Internet Sources for Cases

There are many Internet sites that offer the full text of court opinions free of charge.

These sites are best used to access recent decisions when the case name or date is known. Free Internet sources are generally not recommended for subject research because the sites are not comprehensive and subject searching is not as sophisticated. 

For a listing of free sources of case law, see our Free and Low Cost Legal Research Guide .

Running time: 3:01 minutes

Created/updated: May 2022 Last reviewed: June 2024

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• © Georgetown University Law Library. These guides may be used for educational purposes, as long as proper credit is given. These guides may not be sold. Any comments, suggestions, or requests to republish or adapt a guide should be submitted using the Research Guides Comments form . Proper credit includes the statement: Written by, or adapted from, Georgetown Law Library (current as of .....).
• Last Updated: Sep 26, 2024 11:10 AM
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Legal Research

• Statutory Law
• Regulations
• Secondary sources
• Citing Legal Resources

Case Law Resources

An interdisciplinary, international, full-text database of over 18,000 sources including newspapers, journals, wire services, newsletters, company reports and SEC filings, case law, government documents, transcripts of broadcasts, and selected reference works.

• Google Scholar for Case Law Google Scholar offers an extensive database of state and federal cases, including U.S. Supreme Court Opinions, U.S. Federal District, Appellate, Tax, and Bankruptcy Court Opinions, U.S. State Appellate and Supreme Court Opinions, Scholarly articles, papers, and reports. To get started, select the “case law” radio button, and choose your search terms.
• Caselaw Access Project The Caselaw Access Project (CAP), maintained by the Harvard Law School Library Innovation Lab, includes "all official, book-published United States case law — every volume designated as an official report of decisions by a court within the United States...[including] all state courts, federal courts, and territorial courts for American Samoa, Dakota Territory, Guam, Native American Courts, Navajo Nation, and the Northern Mariana Islands." As of the publication of this guide, CAP "currently included all volumes published through 2020 with new data releases on a rolling basis at the beginning of each year."
• CourtListener Court Listener is a free and publicly accessible online platform that provides a collection of legal resources and court documents, including court opinions and case law from various jurisdictions in the United States. It includes PACER data (the RECAP Archive), opinions, or oral argument recordings.
• FindLaw Caselaw Summaries Archive FindLaw provides a database of case law from the U.S. Supreme Court and U.S. Circuit Courts of Appeal, as well as several state supreme courts. It includes U.S. Supreme Court Opinions, U.S. Federal Appellate Court Opinions and U.S. State Supreme, Appellate and Trial Court Opinions. Search for case summaries or by jurisdiction.
• FindLaw Jurisdiction Search FindLaw provides a database of case law from the U.S. Supreme Court and U.S. Circuit Courts of Appeal, as well as several state supreme courts. It includes U.S. Supreme Court Opinions, U.S. Federal Appellate Court Opinions and U.S. State Supreme, Appellate and Trial Court Opinions. Search for case summaries or by jurisdiction.
• Justia Justia offers cases from the U.S. Supreme Court, U.S. Circuit Courts of Appeal, and U.S. District Courts. Additionally, you may find links to many state supreme court and intermediate courts of appeal cases. Content includes U.S. Supreme Court Opinions, U.S. Federal Appellate & District Court Opinions, Selected U.S. Federal Appellate & District Court dockets and orders and U.S. State Supreme & Appellate Court Opinions.
• PACER (Public Access to Court Electronic Records) PACER is a nationwide database for accessing federal court documents, including case dockets. It covers U.S. District Courts, Bankruptcy Courts, and the U.S. Court of Appeals. Users can search for and access federal case dockets and documents for a fee.
• Ravel Law Public Case Access "This new Public Case Access site was created as a result of a collaboration between the Harvard Law School Library and Ravel Law. The company supported the library in its work to digitize 40,000 printed volumes of cases, comprised of over forty million pages of court decisions, including original materials from cases that predate the U.S. Constitution."
• The RECAP Archive Part of CourtListener, RECAP provides access to millions of PACER documents and dockets.

State Courts

• LLI Listing by Jurisdiction The Legal Information Institute provides a comprehensive list of states and links to their legal resources and websites.
• State Court Websites This page provides a list of various state court system websites by state.
• Pennsylvania Judiciary Web Portal The Pennsylvania Judiciary Web Portal provides the public with access to various aspects of court information, including appellate courts, common pleas courts and magisterial district court docket sheets; common pleas courts and magisterial district court calendars; and PAePay.
• Supreme Court of Pennsylvania Opinions

US Supreme Court

• US Reports he opinions of the Supreme Court of the United States are published officially in the United States Reports.
• US Reports through HeinOnline
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