"In the spring of 2009, the Department of Homeland Security (DHS) issued new guidance on immigration-related worksite enforcement. In the words of DHS, the updated guidance 'reflects a renewed Department-wide focus targeting criminal aliens and employers who cultivate illegal workplaces by breaking the country's laws and knowingly hiring illegal workers.' Under the guidelines, DHS 'will use all available civil and administrative tools, including civil fines and debarment, to penalize and deter illegal employment.' According to 2008 estimates, there are some 8.3 million unauthorized workers in the U.S. civilian labor force. DHS's U.S. Immigration and Customs Enforcement (ICE) is responsible for immigration-related worksite enforcement, or enforcement of the prohibitions on unauthorized employment in Section 274A of the Immigration and Nationality Act (INA). The INA §274A provisions, sometimes referred to as employer sanctions, make it unlawful for an employer to knowingly hire, recruit or refer for a fee, or continue to employ an alien who is not authorized to be so employed. Today, ICE's worksite enforcement program is focused primarily on cases that involve critical infrastructure facilities and cases involving employers who commit 'egregious violations' of criminal statutes and engage in worker exploitation."
CRS Report for Congress, R40002