Arizona v. United States, 567 U.S. 387 (Jun. 25, 2012)

The Court held that federal law preempted three of four provisions of Arizona’s immigration statute. Four provisions of the Arizona law were at issue. One section made failure to comply with federal alien registration requirements a state misdemeanor. A second section made it a misdemeanor for an unauthorized alien to seek or engage in work in Arizona. A third section authorized officers to arrest without a warrant a person “the officer has probable cause to believe . . . has committed any public offense that makes the person removable from the United States.” A fourth section provided that officers who conduct a stop, detention, or arrest must in some circumstances make efforts to  verify the person’s immigration status with the Federal Government. The Court held that the first three provisions were preempted by federal law but that it was improper to enjoin the fourth provision “before the state courts had an opportunity to construe it and without some showing that enforcement of the provision in fact conflicts with federal immigration law and its objectives.”