LibGuides: 1L Legal Research Primer: Headnotes and the Key Number System

Headnotes

Summarize all points of law in a case.
Created by editors at West and Lexis as a research tool.
- Not part of the text of the case – do not cite them.
Helpful for navigating within a case and expanding your research
The number to the left of the headnote links to where that issue is addressed in the case.
“Cases that cite this headnote” links to the citing references that address this particular point of law.
In Westlaw, headnotes link to the West Key Number System

A classification system that divides the law into 414 topics and more than 98,000 legal issues.
Uniform system and all published cases in Westlaw are indexed to it. At least 1 Key Number is assigned to every point of law in every published case.
- Proprietary to Westlaw. Lexis uses a similar system called Topics.
Facilitates finding cases on a legal issue in any jurisdiction.
You can access the Key Number System through the Headnotes
- Advantage: Your search has already identified numbers that are likely to be relevant
You can also access the full system from the Content Types page
- Advantage: You can see the full range of possible Key Number topics

Key Number system the outline of the law; Key Cite is a citator.
Key Numbers are used to find cases by facilitating searching for cases on a particular legal issue
Key Cite is used to validate and update the law.
Don’t be confused by the similarity of the names.