The Mann Act punished “any person who shall knowingly transport or cause to be transported, or aid or assist in obtaining transportation for . . . any woman or girl for the purpose of prostitution or debauchery, or for any other immoral purpose.” The phrase “any other immoral purpose” appeared to include more than large-scale commercialized or coercive prostitution. Almost immediately, the government applied it to consenting fornicators and adulterers, absent any coercion or commercial exchange. In the case of Hoke v. United States (1913), Justice McKenna admitted that “our dual form of government has its perplexities” but concluded that “surely if the facility of interstate transportation can be taken away from the demoralization of lotteries, the debasement of obscene literature, the contagion of diseased cattle or persons, the impurity of food and drugs, the like facility can be taken away from the systematic enticement to and the enslavement in prostitution and debauchery of women, and, more insistently, of girls.” In acting against these evils, Congress “may adopt not only means necessary but convenient.”
The Hoke case involved, if not coercive “white slavery,” at least commercial prostitution. The Court subsequently sustained prosecutions of a noncommercial nature. Shortly after Woodrow Wilson took office, Drew Caminetti, the son of his immigration commissioner, was prosecuted for traveling across state lines and engaging in sexual relations with a woman not his wife. The relationship was completely voluntary and not commercial. The Justice Department could hardly discontinue the case, begun under the previous Republican administration, lest it give an impression of political favoritism. In a 5–3 decision, the Court upheld this application of the Mann Act. The majority declared that it must abide by the plain words of the act, that any “immoral purpose” was enough.
Justice McKenna for the dissenters claimed that the “White Slave Traffic Act” title and legislative history showed that Congress intended to reach only “commercialized vice, immoralities having a mercenary purpose . . . vice as a business.” “Everybody knows that there is a difference between the occasional immoralities of men and women and that systematized and mercenary immorality epitomized in the statute’s graphic phrase, ‘white slave traffic.’” Nevertheless, Mann congratulated Justice William R. Day for his proper interpretation of the act. And there was enough confusion or ambivalence in the public mind as to what really defined “prostitution” to sustain this reading of the act. There would be nearly 5,000 Mann Act convictions over the next decade, most of which were noncommercial.
The Mann Act showed how far the federal police power had been extended. The great Chief Justice John Marshall, in the 1824 case Gibbons v. Ogden, had defined commerce as “intercourse.” Now his successors held that intercourse was commerce.
— Paul Moreno is the director of academic programs at Hillsdale College’s Kirby Center for Constitutional Studies and Citizenship. This article is adapted from his 2013 book The American State from the Civil War to the New Deal: The Twilight of Constitutionalism and the Triumph of Progressivism.