The Justice Dept. has filed a lawsuit seeking to stop Arizona’s new immigration law from taking effect, contending the state statute is unconstitutional and will “undermine” federal immigration enforcement. Arizona Senate Bill 1070, enacted on April 23, is to take effect on July 29. It directs police, while stopping an individual, to try to determine that person’s immigration status when there is “reasonable suspicion” that he or she is in the U.S. illegally. The Justice Dept.’s lawsuit, filed on July 6 in federal district court in Arizona against the state and Gov. Janice K. Brewer (R), says, “In our constitutional system, the federal government has preeminent authority to regulate immigration matters.”

President Obama criticized the Arizona law in a July 1 speech, calling it “divisive” and saying it puts severe pressure on local law enforcement. Obama also called for comprehensive federal immigration legislation. But in the short time left in the current congressional session and with little indication that votes are in the Senate to tackle such a contentious issue, it is unlikely an immigration bill will pass this year.