Companies that run prisons for profit have boosted lobbying efforts in the past decade and enjoy growing influence over the U.S. immigration detention system, the Detention Watch Network says in a new report.

"For years, private prison firms have played a critical role in shaping public policy around immigration detention, pursuing the bottom line at the expense of basic civil rights and taxpayer dollars," DWN's director of Policy and Advocacy, Emily Tucker, said in a statement.

Three of the five private corporations that hold contracts with the U.S. Immigration and Customs Enforcement and for which data on political lobbying is available invested $20.43 million in such efforts between 1999 and 2009.

The largest for-profit prison company in the United States, Corrections Corporation of America, spent by far the most (a little more than $18 million), while GEO Group Inc. spent $2.06 million.

"This data highlights deep corporate investment in the detention business, raising concerns about how the corporate profit-motive is fueling the expansion of the detention system as a whole," Tucker said.

The companies lobbied Congress and executive branch elements such as ICE and the Justice Department.

In CCA's case, the report said it also lobbied the Departments of Labor and Interior.

DWN's study also found that these corporations have pushed for - and even drafted - anti-immigrant law and policy at the state and local level.

But DWN said this initial data is "only the tip of the iceberg" and that "more research is needed in order to determine the extent to which the private prison lobby is responsible for increasingly anti-immigrant policies being enacted at the federal and state levels."

According to the report, abuse and mismanagement complaints have come to light at immigrant detention centers run by CCA and GEO, even leading in some cases to the termination of the companies' contracts.

"ICE has called for sweeping changes in the immigration detention system," Tucker said. "Yet they continue to partner with private prison firms that are part of the problem.

The number of people held in immigration detention has skyrocketed since the 1990s. On any given day, the ICE locks up close to 33,000 people, while the annual cost of the detentions reached $1.7 billion in 2009.

Close to 2.5 million people have passed through immigration detention facilities since 2003.

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