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Levin College of Law

Conducting Legal Research

Resources and tips for conducting legal research .


When you expand a primary source, you use headnotes and the indexing systems of Westlaw or Lexis to find additional primary sources that are related to your original primary source.

Expanding a primary source on Westlaw or Lexis uses:

  • Headnotes
  • Case Indexing system (Key Numbers or Topics)
  • Citators (KeyCite or Shepards)
  • Table of Authorities

Why Should I Care About Headnotes?

Because headnotes:

    Tell you what is discussed in a case.
  • Link you to the discussion in the case so that you can read the legal concept in context.
  • Help you expand your research by linking you to other cases with that same legal concept.
  • Allow you to restrict your Shepard’s/KeyCite report by legal concept, thus helping you narrow the cases that you really need to read to validate your case.
  • Work behind the scenes to help the Lexis and Westlaw algorithms find relevant materials for your search.
  • Finally, headnotes, and the indexing system, allow you to expand and update your primary sources.

Headnotes & Indexing


  • Provide an outline for a case.
  • Identify discrete legal concepts within a case.
  • Preview the legal topics of a case.
  • Are unique to each case.

In Westlaw, attorney-editors examine a case, then write the headnotes for that case, although headnote language typically tracks the court's opinion.

Example: Headnote 11 in Roe v. Wade states "Where certain fundamental rights are involved, regulation limiting these rights may be justified only by a compelling state interest and the legislative enactments must be narrowly drawn to express only legitimate state interests at stake."

In Lexis, attorney-editors pull language directly from a case to create a headnote for that case.

Example: Headnote 5 in Roe v. Wade states: "The United States Constitution does not explicitly mention any right of privacy. A right of personal privacy, or a guarantee of certain areas or zones of privacy, however, does exist under the United States Constitution."


  • Provides an outline/organizational scheme for all legal topics.
  • Drills down from broad topics (such as criminal law) to narrower topics (criminal law > murder > trial > right to trial by jury).
  • Assigns each headnote from a case to a specific, discrete legal topic.
  • Applies to the entire system of cases; not unique to each case.

Westlaw began indexing case law concepts in the late nineteenth century, resulting in what is now the West Topic and KeyNumber system. In the West system, Topics constitute large areas of law, such as Constitutional Law. Within each topic, discrete legal concepts are identified, then assigned a number. Most topics contain several subtopics, which allows a researcher to drill down through the system to identify the most relevant KeyNumber.

Example: West’s Key Number Constitutional Law 92k1053, Strict or Heightened Scrutiny: Compelling Interest, will pull all cases that West’s editors have identified as containing that discrete legal concept. The path to that Key Number is Constitutional Law > Constitutional Rights, in General,> In General > Strict or Heightened Scrutiny: Compelling Interest.

Lexis has a similar system, but it is not as sophisticated as Westlaw's. Lexis calls it the Topic System.

Example: Lexis's Topic Constitutional Law > Substantive Due Process > Privacy > General Overview will pull all cases that Lexis has determined fall within that specific legal concept.