In an increasingly familiar pattern of the federal government challenging tough new state immigration laws, the U.S. Justice Department filed a lawsuit on Monday in an effort to halt an Alabama measure that has been described as the toughest in the nation.

Justice Department lawyers charged that the law sought to usurp the federal government's authority by granting local law enforcement greatly expanded enforcement powers and by setting state immigration policy that diverged from and in some cases conflicted with federal policy.

"To put it in terms we relate to here in Alabama, you can only have one quarterback in a football game. In immigration, the federal government is the quarterback," said Joyce Vance, U.S. Attorney for the Northern District of Alabama.

The law empowers police officers to detain anyone who appears to be an undocumented immigrant, continuing a precedent established in a controversial Arizona law that touched off a wave of stringent state laws from Georgia to Utah. But the Alabama law goes further than others by requiring immigrants to verify their status before they can enroll their children in public school or seek public housing, and by leveling penalties at people who house or transport undocumented immigrants.

Opponents have criticized the law as discriminatory, and several civil rights groups have already taken legal action after charging that it violates the constitution's Equal Protection Clause. The state lawmakers who passed the law counter that they are enforcing the law when the federal government is unwilling to do so.

"The Obama administration and the federal bureaucrats have turned a blind eye toward the immigration issue and refuse to fulfill their constitutional duty to enforce laws already on the books," said Republican State Rep. Micky Hammon, the bill's sponsor. "Now, they want to block our efforts to secure Alabama's borders and prevent our jobs and taxpayer dollars from disappearing into the abyss that illegal immigration causes."