Common law
The common lawso named because it was "common" to all the king's courts across Englandoriginated in the practices of the courts of the English kings in the centuries following the Norman Conquest in 1066. Prior to the Norman Conquest, much of England's legal business took place in the local folk courts of its various shires and hundreds. A variety of other individual courts also existed across the land: urban boroughs and merchant fairs held their own courts, as did the universities of Oxford and Cambridge, and large landholders also held their own manorial and seigniorial courts as needed. Additionally, the Catholic Church operated its own court system that adjudicated issues of canon law.
Common law copyright
"Common law copyright" is also the term used in the United States to refer to most state law copyright claims. In 1978, Section 301 took effect, preempting all state common law copyright claims that fall under subject matter in Section 102 (Subject matter of copyright: In general) or Section 103 (Subject matter of copyright: Compilations and derivative works) except for sound recordings fixed before February 15, 1972. This leaves a sizable amount of work that still falls under a mixture of state statutes and common law copyright.