A federal district court has enjoined enforcement of all of the major portions of a controversial Arizona immigration law, including a provision that authorized police officers to check the immigrant status of individuals suspected of criminal activity. The ruling will not surprise most immigration and constitutional law experts. Supreme Court doctrine gives the federal government wide authority over immigration issues. Conflicting state law is preempted by the Supremacy Clause of the Constitution.
The court ruling, however, only grants a preliminary injunction. This kind of injunction will bar enforcement of portions of the law until the court issues a final ruling on its validity. The issuance of a preliminary injunction, however, means that the government has proven that there is a "likelihood" that it will prevail on the merits of its argument that federal law preempts the Arizona statute.