English law
Common law is a term with historical origins in the legal system of England. It denotes, in the first place, the judge-made law that developed from the early Middle Ages as described in a work published at the end of the 19th century, "The History of English Law before the Time of Edward I", in which Pollock and Maitland expanded the work of Coke (17th century) and Blackstone (18th century). Specifically, the law developed in England's Court of Common Pleas and other common law courts, which became also the law of the colonies settled initially under the crown of England or, later, of the United Kingdom, in North America and elsewhere; and this law as further developed after those courts in England were reorganised by the Supreme Court of Judicature Acts passed in the 1870s, and developed independently, in the legal systems of the United States and other jurisdictions, after their independence from the United Kingdom, before and after the 1870s. The term is used, in the second place, to denote the law developed by those courts, in the same periods (pre-colonial, colonial and post-colonial), as distinct from within the jurisdiction, or former jurisdiction, of other courts in England: the Court of Chancery, the ecclesiastical courts, and the Admiralty court.
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.