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
As used by non-lawyers in popular culture, the term "common law" connotes law based on ancient and unwritten universal custom of the people. The "ancient unwritten universal custom" view was the view among lawyers and judges from the earliest times to the mid-19th century. But for 100 years, lawyers and judges have recognized that the "ancient unwritten universal custom" view does not accord with the facts of the origin and growth of the law, and it is not held within the legal profession today.
Under the modern view, “common law” is not grounded in “custom” or "ancient usage", but rather acquires force of law instantly (without the delay implied by the term "custom" or "ancient") when pronounced by a higher court, because and to the extent the proposition is stated in judicial opinion. From the earliest times through the late 19th century, the dominant theory was that the common law was a pre-existent law or system of rules, a social standard of justice that existed in the habits, customs, and thoughts of the people. Under this older view, the legal profession considered it no part of a judge's duty to make new or change existing law, but only to expound and apply the old. By the early 20th century, largely at the urging of Oliver Wendell Holmes (as discussed throughout this article), this view had fallen into the minority view: Holmes pointed out that the older view worked undesirable and unjust results, and hampered a proper development of the law. In the century since Holmes, the dominant understanding has been that common law “decisions are themselves law, or rather the rules which the courts lay down in making the decisions constitute law”. Holmes wrote in a 1917 opinion, “The common law is not a brooding omnipresence in the sky, but the articulate voice of some sovereign or quasi sovereign that can be identified." Among legal professionals (lawyers and judges), the change in understanding occurred in the late 19th and early 20th centuries (as explained later in this article), though lay dictionaries were decades behind in recognizing the change.