Some of you may also have been tracking the King v. Burwell and Halbig v. Burwell cases as they have worked their way up to the 4th Circuit and D.C. Circuit, respectively, on the question of whether government tax credits for exchange purchases should only be available to states with state established and operated insurance exchanges and not to those purchasing through the federal exchange. The IRS has interpreted Section 36B broadly to authorize the subsidy for insurance purchased under the federal exchange.
In some ways this is a dispute about administrative law (and laugh I did to see the King opinion forwarded to me first by fellow law professors under the heading "the other shoe drops" only to be followed two hours later by the Halbig opinion -- anybody else hear the third shoe dropping?) and agency interpretation of Congressional intent in the face of inartful drafting. In another way, of course, this case is about trying to bring a referendum on the ACA back before the Supreme Court or, at the very least, to deny the annual renewal of previously provided government funded subsidies for approximately six or seven million Americans who purchase through the federal exchange with federal subsidies.