The U.S. Department of Justice has filed a challenge to the state of Arizona’s recently passed immigration law, S.B. 1070, in federal court.

The Arizona law, called the Support Our Law Enforcement and Safe Neighborhoods Act and scheduled to take effect on July 29, is already the target of at least five other lawsuits filed by civil rights and other groups.

In its suit, filed July 7, the DOJ charges that the Arizona law conflicts with federal law, would disrupt federal immigration enforcement, and would lead to local police harassment of those who cannot prove lawful status. DOJ officials expect a hearing within the next two weeks on their motion for a preliminary injunction blocking the law from going into effect.

The DOJ cites the legal doctrine of "preemption" in its complaint. Preemption is based on the U.S. Constitution’s supremacy clause and provides that federal law trumps state statutes. The DOJ argues that because the federal government has "preeminent authority to regulate immigration matters," the Arizona law must be struck down. Additionally, on the more practical side, the DOJ argues that the Arizona law would unduly burden federal agencies charged with immigration enforcement. Enforcement of the Arizona law would result in Arizona referring so many illegal immigrants for deportation, the lawsuit argues, that federal officials would lose focus on top priority targets, such as immigrants involved in terrorism or other crimes. The suit also claims that the Arizona law would overburden local law enforcement officials.

Although the lawsuit mentions potential "detention and harassment" of U.S. citizens and immigrants who do not carry identification documents, it does not argue that the law would lead to racial profiling.

An official press release, along with copies of the complaint and supporting documents, can be found at the Department of Justice website: