Legal Research Strategy

This guide is intended for graduate level students and staff at the Harvard University who are interested in conducting basic legal research but do not have online access to the Westlaw, Lexis Advance or Bloomberg Law databases, which are restricted to Harvard Law School affiliates. Westlaw can be used at the HLS library.

Start your research by reading a legal encyclopedia, handbook, treatise, and other book or article (often referred to as "secondary sources") before looking at the actual text of the law. Why?

  • Secondary sources will help you to identify the primary law (laws, regulations, and cases) that applies to topic.
  • Secondary sources provide an overview, summary, synthesis and explanation of the law as well as analysis and critique.
  • Secondary sources help you to identify subject headings, key numbers, and legal concepts and terms to help you search for how primary law materials.

To find a book, search in our catalog, HOLLIS

Harvard Law School Library, Secondary Sources explain and provide links to secondary sources. The American Jurisprudence 2nd (legal encyclopedia) can be searched within Nexis Uni. 

Primary law is not binding in every jurisdiction. Cases can be overturned in the courts. Statutes and regulations can be repealed or expire. Use up-to-date secondary sources to see if the primary law is still in force.You can conduct a "cite check" or Shepardize a cite in a database like Nexis Uni to determine if a law, statute or regulation is still good law. Federal regulations can be checked using the Electronic Code of Federal Regulations (eCFR).  Learn how with the E-CFR tutorial.

Searching for Articles in Law Reviews

The two databases listed below, Nexis-Uni and HeinOnline, are full text databases.  The other four databases are indexes, with the last one to foreign legal periodicals.  The Index to Legal Periodicals and Books, published by H.W. Wilson, was created by the American Association of Law Libraries. The AALL continued this index in print as the Current Law Index and LegalTrac is its expanded online version, published by Gale. HeinOnline Law Journal Library database contains several indexes and finding tools. The four indexes differ in the number and types of documents indexed, links to full text, date range, and subject headings.

If you are new to legal research and these databases, save time and search more effectively by watching a video demo, reading the search tips or  "Libguide", or asking a librarian.

Alumni access to HeinOnline Law Journal Library

Use advanced search to search by topic, title or citation. Enter a term in "Search by PathFinder Subject" to bring all items indexed under that term.  Alternatively, use Pathfinder subjects to browse subjects by text or interactive graphic. Pathfinder subjects also appears in search results.  How to Browse and Search with PathFinder video (about 5 min.)

General Legal Databases

These expansive databases include a combination of primary and secondary law resources.The terms "primary law" and "primary authority" in  refer to categories of legal texts (statutes and codes, cases, regulations, and treaties) created by legislative bodies, courts, and agencies that taken together are the legal authorities that constitute "the law." In most cases, you should start with secondary sources such as law review articles or books to help you identify important primary law. Search in HOLLIS for books on your legal topic.

Citation Guides

Legislative News & History

News & Tracking

Legislative History

US Law

Federal Laws & Regulations

Listing of what is available at govinfo and links to other legislative, executive and judicial process resources.  The Catalog of U.S. Government Publications (CGP), a finding tool for government publications (from July 1976 -present), includes records for print and content available on govinfo and links to govinfo for access to these publications.

States Laws and Regulations

For additional sources, visit the Harvard Law School Comparing State Laws and Constitutions research guide.

City/County Codes & Ordinances

There is no easy way to search all municipal codes at the same time. This HKS Library Fast Answer provides detailed instructions for locating municipal ordinances or codes in Nexis Uni. Please note that major metropolitan areas may have town, city and/or county ordinances that apply depending on what part of the metropolitan area you are researching. In some areas, you may have county and city codes that apply.

Search for reputable NGOs and think tanks in your policy area as they may have expert practionerys that monitor changes to state and local code. 

Other free resources that provide access to ordinances/codes are listed below:

https://library.municode.com/ (links to county/local codes where available),

Case Law


Foreign & International



Foreign & International Law

Other Guides

Research Guides from other Harvard Libraries

Law Librarians at the Harvard Law Library have authored a large number of specialized legal research guides on topics of interest to members of the Harvard Law School community. They can be viewed at http://guides.library.harvard.edu/law

Some introductory legal research guides are highlighted below:

Non-Harvard State Legal Research Guides

These guides will provide links to their own catalogs or login pages.  Check HOLLIS to see if the resources are available to access the content.