Although the law was created to stop forced
sexual slavery of women, the most common initial use of the Mann Act was to prosecute men for having sex with underage females. The 1948 prosecution of Frank LaSalle for abducting
Florence Sally Horner is believed to have been an inspiration for
Vladimir Nabokov in writing his novel
Lolita. Humbert Humbert, the narrator, at one point explicitly refers to LaSalle. The Mann Act has also been used by the U.S. federal government to prosecute polygamists such as
Mormon fundamentalists.
Bigamy is illegal in the U.S. and all states have
antipolygamy laws.
Colorado City, Arizona;
Hildale, Utah;
Bountiful, British Columbia, northern
Mexico are historic locations of several Mormon sects that practiced polygamy, although
The Church of Jesus Christ of Latter-day Saints has
expressly forbidden polygamy since the start of the 20th century. Sect leaders and individuals have been charged under the Mann Act when "wives" are transported across the Utah–Arizona state line or the U.S.–Canadian and U.S.–Mexican borders. •
Dušan Popov, a World War II Allied double agent with a "
James Bond" lifestyle, was threatened with arrest under the Mann Act. • Individuals associated with the
Fundamentalist Church of Jesus Christ of Latter-Day Saints (FLDS), such as
Warren Jeffs and
Merril Jessop have refused to answer questions during
depositions and court hearings, citing the
5th Amendment, over concerns of
self-incrimination related to "potential state investigation still ongoing, as well as criminal investigations under the Mann Act out of the U.S. Attorney's Office."
Mann Act case decisions by the United States Supreme Court •
Hoke v. United States, . The Court held that Congress could not regulate prostitution
per se, as that was strictly the province of the states. Congress could, however, regulate interstate travel for purposes of prostitution or "immoral purposes". •
Athanasaw v. United States, . The Court decided that the law was not limited strictly to prostitution, but to "debauchery" as well. • In a 1915 ruling, the Court determined that it is not impossible for a victim of the Act to be charged with conspiracy under specific circumstances. The requirements for conspiracy by a victim of the Act were limited in a 1932 ruling. •
Caminetti v. United States, . In 1917, the Court decided that the Mann Act did not apply strictly to purposes of prostitution, but to other noncommercial consensual sexual liaisons; thus consensual extramarital sex fell within the category of "immoral sex". • In 1932, the Court ruled that consent by the victim to their own transportation does not constitute conspiracy or culpability under the Act. •
Cleveland v. United States, . The Court decided that a man can be prosecuted under the Mann Act even when married to the woman if the marriage is polygamous; therefore, in 1946, polygamous marriage was determined to be an "immoral purpose". •
Bell v. United States, . The Court decided that simultaneous transportation of two women across state lines constituted only one violation of the Mann Act, not two violations. • The Court affirmed that a victim can be compelled to testify against a spouse who violated the Act, in exception to the common law spousal privilege rule. ==Congressional amendments to the law==