In October, the U.S. Department of Justice challenged South Carolina's immigration law in federal court, charging that parts of the law are "unconstitutional and interfere with the federal government's authority to set and enforce immigration policy."
In April, the Justice Department succeeded in blocking some provisions of the newly enacted Arizona immigration law, and in October, some of Alabama's controversial provisions were temporarily blocked. Last month, the federal government sued Utah.
"A patchwork of immigration laws is not the answer and will only create further problems in our immigration system," Attorney General Eric Holder said in a statement Nov. 22. "The federal government is the chief enforcer of immigration laws, and while we appreciate cooperation from states, which remains important, it is clearly unconstitutional for a state to set its own immigration policy."
South Carolina officials, including Gov. Nikki Haley, echoing the concerns of leaders in other states, say that local authorities cannot wait any more for the federal government to institute comprehensive immigration reform and must act now to secure borders and protect citizens and legal residents.
"If the Feds were doing their job, we wouldn't have had to address illegal immigration reform at the state level," Haley spokesman Rob Godfrey said recently.
The Obama administration has ramped up deportation actions.
About 1.1 million illegal immigrants have been deported since the beginning of 2009, and the Department of Homeland Security is dealing with a backlog of about 300,000 cases. By comparison, a total of 1.57 million were deported during President George W. Bush's two terms.
In Arizona, some police officers have complained that the 2010 immigration law is unfair and unrealistic. "It drives a wedge between us and the community, where we have to get our information," Roberto Villasenor, Tucson's chief of police, told National Public Radio last year.
The law was drafted with input from the private prison industry, NPR reported last October.
In Alabama, farmers have spoken of serious economic impacts, including a shortage of workers and whole crops rotting in the fields.
The state could see its economy contract by tens of millions of dollars and lose more than $130 million in tax revenue if its new laws effectively remove undocumented immigrants from the state, according to a report released last month by the University of Alabama's Center for Business and Economic Research and calculations published by the American Immigration Council's Immigration Policy Center.
In South Carolina, tax revenues (property, income and sales) from unauthorized immigrants amounted to about $43.7 million in 2010, according to the Immigration Policy Center.
Nationally, the number of illegal immigrants appears to have declined since the beginning of the 2008 recession, from about 12 million to 11 million, with migration flows slowing, according to government estimates.
The Southeast has seen an influx of illegal immigrants in recent years, most of whom have been lured by agriculture and construction jobs, studies have shown.
Finding a reliable, up-to-date figure for the size of South Carolina's undocumented population is difficult; the 2004 U.S. Census estimated there were 36,000 in the state.