The decision in U.S. v. Arizona finds several provisions of Arizona law preempted, mainly on the ground that they interfere with federal policy. It’s hard to be too critical of a judge who comes to that conclusion when the very agencies charged with making federal policy insist at the top of their lungs that state law is interfering with their policy. That said, the decision has to make some heroic assumptions to find an interference with federal policy.
For example, two provisions of the law required local police to check the immigration status of people whom they arrest or whom they stop on suspicion of violating immigration law. DHS claimed that the provisions would overburden the federal centers that check immigration status and thus would prevent the centers from checking the status of higher priority persons, such as felons. You’d think it would be pretty easy for the feds just to tell the Arizona police, when they call, that the centers will answer Arizona requests only after higher priority requests have been answered. But evidently no one at the document-checking centers can say no. That’s pretty scary. I might want to date them, but I’m not sure I want them enforcing the law.