Oral argument in Armstrong v. Exceptional Child Center

This morning the Supreme Court will hear oral arguments in Armstrong v. Exceptional Child Center. I previewed the case for SCOTUSBlog. My post begins:

The specific dispute in the case is whether the state's Medicaid reimbursements should be invalidated under a provision of federal law, 42 U.S.C. § 1396a(a)(30)(A). But the question underlying that dispute has implications far beyond Medicaid.

That underlying question is whether the Supremacy Clause of the Constitution gives plaintiffs a cause of action to enjoin state action as preempted, even when the preempting statute does not. The case exposes a tension between the two very different ways the Court has viewed causes of action in the constitutional and statutory contexts, and it is unclear which one will prevail.

(Read the rest.)