Obama administration sues to block implementation of controversial Alabama immigration law

``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.

``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,'' according to the lawsuit filed in federal court in Alabama.

The administration argued that federal law preempted the state from adopting its own immigration regime and would interfere 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.