Answered By: Library Reviewer Last Updated: Oct 16, 2014 Views: 5
"The Key Number System is something like a really big interactive outline that works like this: First, the American system of law is broken down into Major Topics -- there are more than 400, including things like Civil Rights, Pretrial Procedure, and Treaties. Each of those topics is divided, in greater and greater detail, into individual units that represent a specific legal concept -- like steps in an outline. Each of the lines (and there are more than 80,000 of them!) has a unique number that allows you to find it on the outline. This number is called a Key Number. The whole outline, along with the case headnotes classified to it, is called the Key Number System."