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The Justice Department has filed a lawsuit against Alabama's new controversial immigration law, essentially fighting Alabama on grounds similar to its legal battle with Arizona over that state's controversial law.

In both cases, the Justice Department argues that the states are overstepping their authority by wading into something that is a strictly federal responsibility: immigration enforcement.

Gov. Robert Bentley signed the Alabama law in June, but it's not set to take effect until Sept. 1. The law makes it a crime to be an undocumented immigrant in Alabama and allows law enforcement to detain individuals they have a "reasonable suspicion" of being in the country illegally. The law also makes it illegal to give undocumented immigrants rides and requires school districts to check on the immigration status of students who enroll.

The law is modeled on Arizona's immigration law, parts of which have been blocked by federal court. It's said to be the strictest state-level immigration law in the country.

The Justice Department, in its filing, says 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.

The American Civil Liberties Union applauded the lawsuit, calling Alabama's immigrant law "draconian" and "anti-immigrant."

The law has already faced lawsuits from civil rights groups and others, and Alabama religious leaders announced Monday their own lawsuit against the law, saying, "the bishops have reason to fear that administering of religious sacraments, which are central to the Christian faith, to known undocumented persons may be criminalized under this law."

The sponsor of the Alabama law, Republican state Rep. Micky Hammon, defended it Monday.

"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.

In a Department of Justice statement, Attorney General Eric Holder and Homeland Security Secretary Janet Napolitano said immigration enforcement is the job of the federal government.

"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 department obtained a preliminary injunction against an Arizona immigration law.

Fox News' Mike Levine and The Associated Press contributed to this report.