Section 1328 prohibits three kinds of sexual activities with respect to aliens: (1) importing aliens for prostitution, (2) holding aliens for prostitution, and (3) keeping, maintaining, controlling, supporting, employing, or harboring aliens for prostitution. Each of the three is a separate crime. See Dalton v. Hunter, 174 F.2d 633 (10th Cir.), cert. denied, 338 U.S. 906 (1949).
The phrase, "in pursuance of such illegal importation," was added to § 1328 in 1910 to establish an interstate commerce nexus because the Supreme Court had held that the statute infringed on state police powers. See Keller v. United States, 213 U.S. 138 (1909). Also, "alien" was substituted for "woman or girl" to make it clear that the statute applied to both sexes. The phrase, "or for any other immoral purpose," probably includes only immoral purposes relating to sex, and not, for example, the selling of babies. See United States v. Baker, 136 F. Supp. 546, 549-550 (S.D.N.Y. 1955).
For a definition of "hold" see United States v. Giuliani, 147 F. 594, 596, 600 (D.Del. 1906). See also 18 U.S.C. § 2424, which provides penalties for failure to register a female brought to the United States from certain countries for immoral purposes.
[cited in USAM 9-73.200]