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GW Law Library
Research Guides

Case Law

Finding Cases

Case law refers to the legal precedent of prior court decisions. 

Before searching for cases, it can be beneficial to gain a general familiarity with the area of law being researched.  Secondary sources are a useful tool to learn more about an unfamiliar area of the law and identify helpful keywords for searching in legal databases. Subject specific secondary sources can be found by consulting a research guide

The following are some subscription databases that can be used for case law research:


Keyword and Advanced Searching:

The subscription databases that can be used for case law research generally have a Google like interface with a single search box.  The most basic search that can be run is a keyword search.  Keywords can be entered in the search box and relevant results will be returned.  To further refine a search, one can restrict by jurisdiction, content type, or practice area either before or after running the search.

Another option is to use the advanced search feature, which can result in more relevant cases being retrieved.  Some of the advanced search features that can be chosen from when searching case law include term frequency, connectors, or field searching.  

Key Number System:

The Key Number System is how Westlaw indexes the law.  The narrowest legal concepts are assigned unique numbers, which are called Key Numbers.  For each case in Westlaw, editors create short paragraphs that appear prior to the opinion on specific points of law, which are called headnotes.  These paragraphs are then assigned at least one Key Number.  Utilizing these Key Numbers, one can search for other related cases that cover that same point of law.  Locating one good case with an on point headnote and key number will help finding other relevant cases.


ALR and Legal Encyclopedias:

American Law Reports (ALR) contain articles, called annotations, that analyze specific, unsettled legal issues in different areas of the law.  Every annotation contains a survey of court decisions from various jurisdictions. 

Legal encyclopedias provide broad background information on a variety of legal topics, in addition to noting citations to leading cases.  For those encyclopedias published by Thomson Reuters/West, they will also include references to Key Numbers, which can be used to locate additional case law on point.  

Other secondary sources will also contain references to case law.  To search other secondary sources see the Journal Articles Research guide or a subject specific research guide.

Free Online Resources




Researching Case Law in Print

For instructions on how to do case law research in print, see the Finding Cases and Interpretation Citations guide.

Case Law Research