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 good
Against that background, the common good became a central concept in the modern tradition of Catholic social teaching, beginning with the foundational document, "Rerum novarum", a papal encyclical by Pope Leo XIII, issued in 1891. This addressed the crisis of the conditions of industrial workers in Europe and argued for a position different from both laissez-faire capitalism and socialism. In this letter, Pope Leo guarantees the right to private property while insisting on the role of collective bargaining to establish a living wage.