Also known as Common Law. The law created by judges when deciding individual disputes or cases. Non-statutory law.
Legal principles that are developed by appellate courts when deciding appeals are collectively termed the case law or common law. Since the 12th century, the common law has been England's primary system of law. When the United States became independent, states adopted the English common law as their law. Since that time, decisions by U.S. courts have developed a body of U.S. case law which has superseded English common law in most areas.
Source: 'Lectric Law Library. (n.d.). Case law. Retrieved from http://www.lectlaw.com/def/c014.htm
When you Shepardize® a case, Nexis Uni provides a report showing every opinion where that case has been referenced, all treatments of the case, and, most importantly, whether or not the case is "good law." If the case has been overruled, it is considered "bad law" and may no longer be cited as a legal precedent. (LexisNexis Academic Help. Shepard's Citations.)
Guide to Using Shepard's Citations
Steps to Shepardize® a case, and guidance in understanding the Shepard's Signal Marker.