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.
Commonwealth v. Hunt
As a result of the spate of convictions against combinations of laborers, the typical narrative of early American labor law states that, prior to "Hunt" in Massachusetts in 1842, peaceable combinations of workingmen to raise wages, shorten hours or ensure employment were illegal in the United States, as they had been under English common law. In England, criminal conspiracy laws were first held to include combinations in restraint of trade in the Court of the Star Chamber early in the 17th Century. The precedent was solidified in 1721 by "The King v. Journeymen Tailors of Cambridge", which found tailors guilty of a conspiracy to raise wages. Leonard Levy went so far as to refer to "Hunt" as the "Magna Carta of American trade-unionism," illustrating its perceived standing as the major point of divergence in the American and English legal treatment of unions which, "removed the stigma of criminality from labor organizations."