Stop Trafficking of Persons Act of 2004 or STOP Act - Amends Federal law with respect to jurisdictional immunity of foreign states to include within the definition of "commercial activity" trafficking in human beings for sexual activity or other purposes.
Amends the Violence Protection Act of 2000 to: (1) include a country's efforts to reduce international sex tourism within its borders among the criteria for determining whether a country is taking serious steps to eliminate trafficking in human beings; and (2) state that nothing in such Act shall be construed to require any federally-funded nongovernmental organization that investigates foreign trafficking activities to notify foreign governments or targets of such investigation's funding source.