This will be found to be interesting:

The common law right to earn a living

Instead, Sutherland was "settling the case in terms that were as purely jural as an opinion could be." The New Deal's infringements on the right to earn a living "offended, deeply, the principles of lawfulness" (Arkes 1994, 82). Such arrangements offended the right of the individual to use her land, her property, or her talents as she saw fit. Far from being examples of judicial activism, cases such as Adkins, Yick Wo, or Lochner were instances in which the Court restrained legislative activism that abridged the right to pursue a lawful occupation--a right sanctified by at least seven hundred years of traditional protection.

To justify the extreme sorts of regulation that constituted the New Deal, it was necessary to overcome that tradition or to deny its existence. In 1937, in the famous "Switch in Time That Saved Nine," the Supreme Court reversed centuries of common law. Whereas courts had formerly presumed against laws infringing on common-law rights, including the right to earn a living, in United States v. Carolene Products the Court held that "regulatory legislation affecting ordinary commercial transactions is not to be pronounced unconstitutional unless in the light of the facts made known or generally assumed it is of such a character as to preclude the assumption that it rests upon some rational basis" (304 U.S. 144 [1937], at 152).

By this decision, the Court divided individual rights into "fundamental" rights and "economic" rights. Yet, as earlier generations had understood, the two cannot be separated. The "economic right" to operate a business had never been based only on economic justifications; rather, it was a form taken by the fundamental right of a person to provide for himself or his family. The spurious nature of the dichotomy in Carolene Products has been sufficiently demonstrated elsewhere (McCloskey 1962, 34-45; Pilon 1999; Siegan 1995), but it is remarkable how, after 1937, the history of the right to earn an honest living has been confused.

With the rise of legal positivism--originated by Roscoe Pound, Oliver Wendell Holmes Jr., Louis Brandeis, and others--the very existence of such a right came to be directly challenged. In McAuliffe v. New Bedford, Holmes wrote, "The petitioner may have a constitutional right to talk politics but he has no constitutional right to be a policeman" (155 Mass. 216 [1892], at 220) This declaration is strictly correct because the common law guarantees only the right to seek employment, not the right to a have particular job, but Holmes's dictum, as Justice William Douglas would later write, "[had] pernicious implications" (Barsky v. Bd. of Regents of the State of New York, 347 U.S. 442 [1954], at 472). Roscoe Pound went further than Holmes, though, insisting that "there never has been at common law any such freedom of contract as [cases such as Lochner or Butcher's Union] postulate." Pound argued that the individual had no right, "by contract, [to] impose substantial restraints upon his [own] liberty" because "[f]reedom to impose these restraints, in the hands of the weak and necessitous, defeats the very end of liberty" (1909, 470-72). In other words, the poor could not be trusted with the right to decide for themselves the number of hours they wished to work.
Kens argues. "Nowhere does the Constitution expressly guarantee a right to engage in a trade or profession" (1997, 117).
Engaging in a trade or profession affects a public interest.
Legislature can just as easily classify a given type of labor as 'a trade, profession, or occupation'.