Supreme Court: preemption of "paper please" portion of Arizona law premature

This morning the U.S. Supreme Court released it's opinion in Arizona v. U.S. 

The Court held that 3 of the 4 challenged provisions of Arizona SB 1070 were preempted by federal law, but that the controversial §2(B) (commonly referred to as the "papers please" portion of the law) cannot be enjoined "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."

Regarding the "papers please" section of SB 1070, the Court states that:

There is a basic uncertainty about what the law means and how it will be enforced. At this stage, without the benefit of a definitive interpretation from the state courts, it would be inappropriate to assume §2(B) will be construed in a way that creates a conflict with federal law. ... This opinion does not foreclose other preemption and constitutional challenges to the law as interpreted and applied after it goes into effect.

The other 3 sections were held to be preempted. Two of these create state misdemeanor offenses for failing to carry alien registration documents and for unauthorized aliens applying for work or working in Arizona. Section 6 authorizes warrentless arrest of aliens suspected of being removaable.  

 The decision was a 5-3 decision with Justice Kagan not participating.