Tue Jul 6, 5:44 PM ET

The US government on Tuesday filed a lawsuit against Arizona for a controversial immigration law which has been sharply criticized by America's neighbors and by the US administration. "Setting immigration policy and enforcing immigration laws is a national responsibility," US Attorney General Eric Holder said in the statement.

WASHINGTON — The Justice Department Tuesday sued Arizona over its tough new immigration law, charging the state with crossing a "constitutional line" that would undermine the federal government's efforts to monitor illegal aliens.

In its lawsuit, filed in Phoenix , the Justice Department explained that the federal government has the strict and sole authority to create national immigration policy.

" Arizona's immigration policy . . . exceeds a state's role with respect to aliens, interferes with the federal government's balanced administration of the immigration laws, and critically undermines U.S. foreign policy objectives," the department said.

Arizona's law, which seeks "attrition through enforcement," establishes a mandatory system that requires law enforcement officers to verify any given person's legal status if the officer is suspicious of "unlawful presence."

The department asked for a preliminary injunction against the policy to prevent "irreparable harm" to the U.S. The law was signed by Republican Gov. Jan Brewer on April 23 and is slated to take effect on July 29 .

"As a direct result of failed and inconsistent federal enforcement, Arizona is under attack from violent Mexican drug and immigrant smuggling cartels," Brewer said in a statement. Now, Arizona is under attack in federal court from President Obama and his Department of Justice ."

Last week, in his first major speech on the issue, President Barack Obama urged Congress to make a comprehensive immigration overhaul a priority, citing Arizona's law. However, he offered no new specifics or a deadline for enacting a bill.

Arizona's law, the department wrote, would disrupt the national framework and potentially lead other states down a slippery slope of patchwork policies that would "cripple" federal policy.

The law is unconstitutional, the department wrote primarily because "it impermissibly attempts to set immigration policy at the state level and is therefore preempted."

Although the law rightfully seeks to deter "unlawful entry" of illegal aliens, the lawsuit asserts, it ignores all other aspects of federal policy.

The department noted that Arizona's law could potentially result in the "harassment and incarceration" of legal aliens and even U.S. citizens who are stopped by police officers and who lack immediate documentation as proof of legal presence.

The use of extensive resources to target all potential illegal aliens, instead of focusing attention on major threats, conflicts with U.S. policy, the department argued.

"Arizonans are understandably frustrated with illegal immigration, and the federal government has a responsibility to comprehensively address those concerns," said U.S. Attorney General Eric Holder in a press release. "But diverting federal resources away from dangerous aliens such as terrorism suspects and aliens with criminal records will impact the entire country's safety."

Janet Napolitano , the secretary of the Department of Homeland Security , said she vetoed similar pieces of legislation during her two terms as governor of Arizona . She echoed Holder's concerns and added that, if implemented, the Arizona law would undermine "the vital trust between local jurisdictions and the communities they serve."

ON THE WEB

Department of Justice Complaint about Arizona

Department of Justice brief against Arizona

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