Liberty and property are terms which have each received definitions broad enough to cause their connotations in very considerable measure to overlap. Thus in Allgeyer v. Louisiana,42 the court, defining liberty, say: "The liberty mentioned in the Fourteenth Amendment means not only the right of the citizen to be free from the mere physical restraint of his person, as by incarceration, but the term is deemed to embrace the right of the citizen to be free in the engagement of all his faculties; to be free to use them in all lawful ways; to live and work where he will; to earn his livelihood by any lawful calling; to pursue any livelihood or avocation; and for that purpose to enter into all contracts which may be proper, necessary, and essential to his carrying out to a successful conclusion the purposes above mentioned."
With this definition of liberty, may be compared the following definition, by the Supreme Court of Illinois, of property: "The right of property preserved by the Constitution," say the court, "is the right not only to possess and enjoy it, but also to acquire it in any lawful mode, or by following any lawful industrial pursuit which the citizen, in the exercise of the liberty guaranteed, may choose to adopt. Labor is the primary foundation of all wealth. The property which each one has in his own labor is the common heritage. And as an incident to the right to acquire other property, the liberty to enter into contracts by which labor may be employed in such way as the laborer shall deem most beneficial, and of others to employ such labor, is necessarily included in the constitutional guaranty." 43
41 197 U. S. 544; 25 Sup. Ct. Rep. 522; 49 L. ed. 872. 42 165 U. S. 578; 17 Sup. Ct. Rep. 427; 41 L. ed. 832.
The foregoing definitions make it sufficiently plain that contractual rights, as a species of property rights, or as included within the definition of liberty, are fully protected by the due process clauses. In Holden v. Hardy44 there is an explicit statement to this effect.45
The manner in which the rights of property and of liberty, including liberty of contract, are held subject to the exercise of such powers of the State as those of eminent domain, taxation, the regulation of occupations affected with a public interest, and, especially, the police power, is considered passim throughout this treatise, and does not require specific treatment in this place.