United States v. Arizona
United States Court of Appeals for the Ninth Circuit
641 F.3d 339 (2011)
Arizona enacted S.B. 1070 to deter illegal immigration, including provisions requiring police to check immigration status during stops with reasonable suspicion (§ 2(B)), criminalizing failure to carry alien registration documents (§ 3), criminalizing unauthorized aliens soliciting work (§ 5(C)), and authorizing warrantless arrests for removable offenses (§ 6); the federal government (plaintiff) sued to enjoin four provisions as preempted by comprehensive federal immigration law, and the district court granted a preliminary injunction, which Arizona appealed.
Whether a state law establishing a range of immigration-related state offenses and defining state immigration-enforcement authority is preempted where Congress has completely occupied the entire field.