The U.S. Justice Department is filing a lawsuit challenging the constitutionality of Arizona's new law targeting illegal immigrants, setting the stage for a clash between the federal government and state over the nation's toughest immigration crackdown.
The planned lawsuit was confirmed to The Associated Press by a Justice Department official with knowledge of the plans. The official didn't want to be identified before a public announcement planned for later Tuesday.
The lawsuit will argue that Arizona's new measure requiring state and local police to question and possibly arrest illegal immigrants during the enforcement of other laws, like traffic stops, usurps federal authority.
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.
But the filing is likely to have a civil rights component as well, arguing that the Arizona law would lead to police harassment of U.S. citizens and foreigners, said the sources, who spoke on condition of anonymity because the government has not announced its plans. President Obama has warned that the law could violate citizens' civil rights, and Attorney General Eric H. Holder Jr. has expressed concern that it could drive a wedge between police and immigrant communities.