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.
Labor history of the United States
These conditions led to the first labor combination cases in America. Over the first half of the 19th century, there are twenty-three known cases of indictment and prosecution for criminal conspiracy, taking place in six states: Pennsylvania, Maryland, New York, Louisiana, Massachusetts, and Virginia. The central question in these cases was invariably whether workmen in combination would be permitted to use their collective bargaining power to obtain benefits—increased wages, decreased hours, or improved conditions—which were beyond their ability to obtain as individuals. The cases overwhelmingly resulted in convictions. However, in most instances the plaintiffs' desire was to establish favorable precedent, not to impose harsh penalties, and the fines were typically modest.
One of the central themes of the cases prior to the landmark decision in "Commonwealth v. Hunt", which settled the legality of unions, was the applicability of the English common law in post-revolutionary America. Whether the English common law applied—and in particular whether the common law notion that a conspiracy to raise wages was illegal applied—was frequently the subject of debate between the defense and the prosecution. For instance, in "Commonwealth v. Pullis", a case in 1806 against a combination of journeymen cordwainers in Philadelphia for conspiracy to raise their wages, the defense attorneys referred to the common law as arbitrary and unknowable and instead praised the legislature as the embodiment of the democratic promise of the revolution. In ruling that a combination to raise wages was "per se" illegal, Recorder Moses Levy strongly disagreed, writing that "[t]he acts of the legislature form but a small part of that code from which the citizen is to learn his duties . . . [i]t is in the volumes of the common law we are to seek for information in the far greater number, as well as the most important causes that come before our tribunals."