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 Era
The English phrase "common Era" appears at least as early as 1708, and in a 1715 book on astronomy is used interchangeably with "Christian Era" and "Vulgar Era". A 1759 history book uses "common æra" in a generic sense, to refer to the common era of the Jews. The first-so-far found usage of the phrase "before the common era" is in a 1770 work that also uses "common era" and "vulgar era" as synonyms, in a translation of a book originally written in German. The 1797 edition of the Encyclopædia Britannica uses the terms "vulgar era" and "common era" synonymously. In 1835, in his book "Living Oracles", Alexander Campbell, wrote: "The vulgar Era, or Anno Domini; the fourth year of Jesus Christ, the first of which was but eight days", and also refers to the "common era" as a synonym for "vulgar era" with "the fact that our Lord was born on the 4th year before the vulgar era, called Anno Domini, thus making (for example) the 42d year from his birth to correspond with the 38th of the common era..." The "Catholic Encyclopedia" (1909) in at least one article reports all three terms (Christian, Vulgar, Common Era) being commonly understood by the early 20th century.