The Justice Department has decided to file suit against Arizona on the grounds that the state's new immigration law illegally intrudes on federal prerogatives, law enforcement sources said Monday.
The lawsuit, which three sources said could be filed as early as Tuesday, will invoke for its main argument the legal doctrine of "preemption," which is based on the Constitution's supremacy clause and says that federal law trumps state statutes. Justice Department officials believe that enforcing immigration laws is a federal responsibility, the sources said.
A federal lawsuit will dramatically escalate the legal and political battle over the Arizona law, which gives police the power to question anyone if they have a "reasonable suspicion" that the person is an illegal immigrant. The measure has drawn words of condemnation from President Obama and Attorney General Eric H. Holder Jr. and opposition from civil rights groups. It also has prompted at least five other lawsuits. Arizona officials have urged the Obama administration not to sue.