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. The British Empire spread the English legal system to its historical colonies, many of which retain the common law system today. These "common law systems" are legal systems that give great precedential weight to common law, and to the style of reasoning inherited from the English legal system.
Oliver Wendell Holmes Jr.
The common law evolves because civilized society evolves, and judges share the common preconceptions of the governing class. These views endeared Holmes to the later advocates of legal realism, and made him one of the early founders of law and economics jurisprudence. "The Common Law" is the only major scholarly work written by a practicing attorney. Holmes famously contrasted his own scholarship with the abstract doctrines of Christopher Columbus Langdell, dean of Harvard Law School, who viewed the common law as a self-enclosed set of doctrines. Holmes viewed Langdell's work as akin to the German philosophic idealism he had for so long resisted, opposing it with his own scientific materialism.