. Skip to Main Content
It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.
Banner Image

LRAC Legal Research Class Site

West Key Number System Overview

As Mr. West developed his National Reporter System, thousands of cases from all jurisdictions were available for the first time. He realized that he needed to develop a method to allow users to find cases on a specific legal topic.  

In 1848, he developed a classification system called the West Digest System to assist researchers with finding case law on a specific legal issue. On Westlaw, it is now called the West Key Number System.

Classification System

He decided that all legal issues fell into one of 414+ broad topics. Each topic is divided into numerous subtopics, each of which is assigned an individual Key Number. There are over 90,000 Key Numbers!

Using a Key Number to Find Cases on a Specific Topic

The point of this huge and elaborate classification system is to allow a researcher to find cases on a specific topic. 

Finding a Relevant Key Number

You would like to find a relevant Key Number to use to find cases about knowledge of a dog's vicious propensities.

Animals is one of the 414+ topics in the West Key Number System. You can click through the outline to look at increasingly specific key numbers. The most specific one is 28K66.5(2) - Vicious propensities and knowledge thereof.

Using a Relevant Key Number to Find Cases on the Same Topic

Once you find a relevant Key Number, you can click on it to find cases on the same narrow topic in your desired jurisdiction.