The privileges and immunities designated are those which of [natural and inalienable] right belong to the citizens of all free governments. Clearly among these must be place the right to pursue lawful employment in a lawful manner, without other restraint than such as equally affects all persons. Mr. Justice Stephen Field
Justice Stephen Field: Shaping Liberty from the Gold Rush to the Gilded Age, by Paul Kens. University Press of Kansas, 1997.