It is challenging the state's new law that would let police detain those stopped for traffic offenses who they suspect are in the country illegally, a statute described as one of the toughest immigration regulations nationwide.
In a complaint Monday, the U.S. Justice Department said Alabama's law conflicts with federal law and undermines federal immigration priorities. The lawsuit argues that the state law also expands opportunities for police to push immigrants toward jail for various new immigration crimes.
The law is set to take effect Sept. 1. It also makes it a crime to knowingly give a ride or provide shelter to an undocumented immigrant and requires schools to report the immigration status of students. Alabama employers would be required to use a federal system called E-Verify to determine if new workers are in the country legally.
The Justice Department, in its filing in Birmingham federal court, said a state cannot set its own immigration policy and cannot pass laws that conflict with federal immigration laws.
"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.
Already the law is facing mounting opposition.
Also Monday, a coalition of religious leaders challenged its legality. The lawsuit by Roman Catholic, United Methodist and Episcopal bishops says it "makes it a crime to follow God's command to be Good Samaritans."
Last month, a coalition of civil and immigrant rights groups also asked a court to bar the law from taking effect. U.S. District Judge Sharon Blackburn in Birmingham has scheduled a hearing for Aug. 24 to consider that.
The law's sponsor Republican state Rep. Micky Hammon defended it.
"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. 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," Hammon said.
"Allowing hundreds of thousands of illegal immigrants to run unchecked under the radar threatens our homeland security and insults those who come here legally," he added.
The law requires public schools to determine the immigration status of its students and whether they qualify for classes in English as a second language.
Opponents contend that provision could have a chilling effect by — for instance — potentially discouraging parents in the U.S. illegally from enrolling children even if those youngsters are citizens. Officials counter that the state's tough stance won't prohibit any child — undocumented immigrant or not — from enrolling in public school.
"Legislation like this diverts critical law enforcement resources from the most serious threats to public safety," Napolitano said.
The Justice Department's complaint quoted Birmingham police chief A.C. Roper as saying the law would divert scarce resources from local policing priorities to immigration enforcement.
Last year, the justice department obtained a preliminary injunction against a similarly tough Arizona immigration law.
The ACLU's Immigrants' Rights Project director Cecillia Wang said she welcomes the lawsuits. As one of the attorneys in the civil rights lawsuits, she said the various legal challenges highlight the problems with the law that the Legislature passed in June.
"It is a law that really tramples on civil rights, civil liberties and religious freedoms in the state of Alabama," Wang said.
A spokesman for Alabama Republican House Speaker Mike Hubbard said it was disappointing that the federal government has not enforced immigration law.
"If the federal government wants to help it should do its job, close the border and enact serious immigration reform," said Todd Stacy.
Based on reporting by The Associated Press.