WASHINGTON (Reuters) - The Obama administration on Monday sued to block enforcement of Alabama's new immigration law, widely considered to be the toughest measure in the United States to try to crack down on illegal immigrants.
The law, known as H.B. 56, was signed by Republican Governor Robert Bentley in June and is due to take effect on September 1. Civil rights groups brought a separate lawsuit challenging the law about a month ago.
"If allowed to go into effect, H.B. 56's enforcement scheme will conflict with and undermine the federal government's careful balance of immigration enforcement priorities and objectives," administration lawyers said in the lawsuit filed in federal court.
"The scheme will cause the detention and harassment of authorized visitors, immigrants, and citizens who do not have or carry identification documents specified by the statute, or who otherwise will be swept into the ambit of H.B. 56's enforcement-at-all-costs approach," the lawsuit said.
The administration, which sought an injunction to block the law from taking effect, argued that the U.S. Constitution bars the state from adopting its own immigration regime that interferes with the federal immigration system. There are an estimated 11 million illegal immigrants in the United States.
Conservatives have complained that the Obama administration has failed to sufficiently stop the flow of illegal immigrants into the country. Attempts to overhaul federal immigration policy have gone nowhere in the U.S. Congress.
Besides Alabama, Georgia, Arizona, Utah and Indiana are defending new immigration laws in federal court. The Obama administration successfully sued to block Arizona's tough law last year and courts have also put the laws in Georgia, Indiana and Utah temporarily on hold.
"Today's action makes clear that setting immigration policy and enforcing immigration laws is a national responsibility that cannot be addressed through a patchwork of state immigration laws," Attorney General Eric Holder said in a statement.
Alabama Governor Robert Bentley said states that have passed strong immigration measures have done so because the federal government has failed to enforce U.S. immigration law.
Like the Arizona law blocked by the courts last year, the Alabama measure requires police to detain someone they suspect of being in the United States illegally if the person cannot produce proper documentation when stopped for any reason.
The Alabama legislation goes further by making it a crime to knowingly transport or harbor an illegal immigrant. It also requires public schools to determine, by reviewing birth certificates or sworn affidavits, the legal residency status of students upon enrollment.
The law imposes penalties on businesses that knowingly employ someone without legal resident status, and a company's business license could be suspended or revoked. A similar Arizona law was upheld by the U.S. Supreme Court in May.
The Alabama law also requires businesses to use a database called E-Verify to confirm the immigration status of new employees.
(Reporting by James Vicini and Jeremy Pelofsky; Editing by Anthony Boadle)