The Justice Department will seek an injunction to prevent Arizona's tough immigration law from taking effect later this month, according to media reports quoting unnamed law enforcement officials.
To overturn the law, the DOJ will rely on two central arguments, according to the Washington Post. Federal attorneys will argue the legal doctrine of "preemption," which is based on the Constitution's supremacy clause and says that federal law trumps state statues.
The filing will also contain a civil-rights argument that the law would lead to police harassment of U.S. citizens and foreigners.
Arizona's immigration law, which was signed by Gov. Jan Brewer in April, requires officers with a "reasonable suspicion" to question subjects about their immigration status.