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.
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 66.5(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.