The difficulty which American courts have experienced with regard to the treatment of hours of labor is easily understood. They assume the existence of a constitutional principle which protects what is called the freedom of contract. This means that the state must leave the economic side of the labor contract to the free bargaining of the parties concerned; it means from the point of view of the employer that his business is not to be regulated by law in order to secure satisfactory terms to the employe, as the railroad business is regulated to secure fair terms to the shipper or the traveling public; from the point of view of the employe it means that he is free to make the most of his earning capacity, and to work as long as he pleases, or rather, conceding the limited sphere of the police power, as long as is consistent with proper standards of health and safety. The movement for the eight-hour day has, generally speaking, been frankly an economic movement, designed to advance the workman in the social scale, to give him time for recreation, culture, the enjoyment of his home, everything, in short, that is supposed to go with rational leisure, and it has generally been accepted as a principle of American constitutional law, that this consummation was not to be brought about by legislative compulsion. The state was to further the movement only in so far as it had the right to dictate the conditions of employment on work done for the public. Notwithstanding the recognition of this constitutional limitation, there have at all times been large sections of organized labor who would have been glad to enlist the power of the law in the struggle for the shorter workday, and who would welcome any reduction on constitutionally valid grounds as a step in that direction. Hence the appeal for the eight-hour day on public works; and hence the appeal to the police power of the state for the purpose of shortening hours of labor.