The right of personal liberty and the right to acquire and hold property which are protected by the general guaranty of due process of law involve the right to make contracts and to enforce remedies for breach of contract. On the other hand, the legislature in the exercise of its police power for the protection of infants, persons not of sound mind, and in general persons who are not capable of protecting their own interests may regulate the making and enforcement of contracts by and against such persons. The question may arise, therefore, whether a statutory regulation which restricts the making or enforcement of certain classes of contracts is a reasonable exercise of the duty to afford protection to persons incapable of guarding their own interests. Thus the employment of children in factories beyond a specified number of hours per day of labor may be prohibited. Moreover, certain kinds of labor may be injurious except under special restrictions; and the legislature may therefore provide that not more than a specified number of hours of labor per day shall be permitted to be performed by any person in such occupations as mining (Holden v. Hardy). As tending to prevent fraud the legislature may prohibit contracts requiring payment of miners' wages to be made on the basis of the amount of screened coal produced (McLean v. Arkansas). These matters are properly subject to control in the exercise of the police power (see above, § 48); but on the other hand, freedom to labor or to contract with reference to labor not peculiarly injurious, to be performed by persons competent to consult their own interests, cannot be properly restricted by legislation (Lockner v. New York). The general principle is that each person should be allowed to exercise his own discretion as to his private affairs, subject only to such restrictions as are reasonably within the scope of the police power.