Some of the best U.S. Supreme Court precedent for each side comes from cases with similarly strong political shading. States’ rights proponents are relying on 1997’s Printz v. United States, which the court held, in an opinion by Justice Antonin Scalia, that the federal government could not coerce county law enforcement officials from Arizona and Montana to conduct background checks on handgun purchasers while the government assembled a nationwide database. That sort of conscription, Justice Scalia wrote, would breach the Constitution’s scheme of balancing state and federal power by enshrining dual sovereignty.
The Justice Department suit, meanwhile, cites 2012’s Arizona v. United States, which struck down stringent Arizona immigration laws as preempted under the Supremacy Clause. The Supreme Court held, in an opinion by Justice Anthony Kennedy, that Arizona intruded on federal authority over immigration law when it allowed state law enforcement officers to make warrantless arrests of aliens suspected of being in the country illegally. If the Arizona statute were allowed, Justice Kennedy wrote, every state could give itself independent authority to police immigration – and that’s not what Congress intended nor what the Constitution permits.
