Health, safety and morals have always been undisputed titles of the police power, where it is a question of protecting the public at large. The control of the internal arrangements of the workshop in the interest of the employes, who, in theory, entered into it voluntarily, was the great extension of the power of the law achieved by the English factory acts. It is a strange anachronism when we find American courts in the end of the nineteenth century questioning the legitimacy of restrictive legislation intended only for the benefit of the employed, who may be willing to assume the risk,[53] but it is true that it was not until after the middle of the nineteenth century that the English law sanctioned sanitary requirements on behalf of adult employes, and the singling out of adult women for the purpose of such protection met with opposition.[54] At present the validity of the sanitary and safety provisions of factory acts is, in principle, unquestioned, and opponents of such acts have to scrutinize them for constitutional defects in non-essential features. Where such provisions apply to women in particular it is generally because the danger or evil arises out of conditions peculiar to the sex. The limitation of hours of labor is at present the most conspicuous phase of restrictive labor legislation. As applied to men, it has in general been confined to special occupations. In some cases the reason why they were singled out is not apparent. This is true of the laws of some southern states with regard to the employes of cotton or woolen mills, which have not been passed upon by the courts of last resort; in other cases, the inducing motive was the consideration of public safety, as in the limitation of hours of trainmen; in the remaining cases--those of miners and bakers--the legislation sought to justify itself as a measure for the protection of the health of the employes. It is well known that there is a conflict of judicial opinion regarding the validity of this legislation, strongly emphasized by the vacillating attitude of the Supreme Court of the United States, which sustained an eight-hour day for miners and annulled a ten-hour day for bakers.[55] The inconsistency of these two rulings is particularly striking, since it is generally believed that the occupation of bakers is exceptionally unsanitary, and was singled out as such under the delegated powers of regulation committed to the federal council by the German trade code, while the mining of coal under modern conditions is regarded as remarkably immune from occupational disease. In Colorado the eight-hour day for miners was declared unconstitutional.[56]