The work visa program for temporary foreign workers in the United States is “not only the longest-running, but also the largest such program in the world.” Close to one million foreign workers receive work visas each year for both skilled and unskilled temporary jobs in the United States. Nevertheless, the number of foreign workers laboring in the United States that do not have the legal documentation necessary to work in the United States (“undocumented migrant workers”) dwarfs the number of temporary foreign workers that receive visas to work in the United States (“documented migrant workers”). As of 2008, there were an estimated 8.3 million, mostly low-wage and low-skilled, undocumented migrant workers in the U.S. labor force. Some estimates suggest that the number of undocumented migrant workers in the United States may be even higher. Thus, when discussing “migrant worker law,” the laws that affect undocumented migrant workers deserve special attention in the U.S. context.