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.
In 1881, in "The Common Law", Holmes brought together into a coherent whole his earlier articles and lectures concerning the history of the common law, judicial decisions in England and the United States, which he interpreted from the perspective of a practicing lawyer. What counted as law, to a lawyer, was what judges did in particular cases. Law was what the state would enforce, through violence if necessary; echoes of his experience in the Civil War were always present in his writings. Judges decided where and when the force of the state would be brought to bear, and judges in the modern world tended to consult facts and consequences when deciding what conduct to punish. The decisions of judges, viewed over time, determined the rules of conduct, the legal duties, by which all were bound. Judges did not and should not consult any external system of morality, certainly not a system imposed by the Deity.