Attorney General's Annual Report to Congress and Assessment of U.S. Government Activities to Combat Trafficking in Persons Fiscal Year 2008 [open pdf - 3MB]
"The centerpiece of U.S. Government efforts to eliminate human trafficking is the Trafficking Victims Protection Act of 2000 (TVPA), Pub. L. 106-386. […] The TVPA enhanced three aspects of federal government activity to combat TIP: protection, prosecution, and prevention. The TVPA, which was designed to address the needs of foreign victims of trafficking, provided for a range of new protections and assistance for victims of trafficking; it expanded the crimes and enhanced the penalties available to federal investigators and prosecutors pursuing traffickers; and it expanded the U.S. Government's international activities to prevent victims from being trafficked."
U.S. Dept. of State: http://www.state.gov/