King v. Burwell (PDF) is a statutory interpretation case about health care exchanges, but the Elections Clause makes an appearance.
From Justice Scalia's dissent:
To see the error in this reasoning, one need only consider a parallel provision from our Constitution: “The Times, Places and Manner of holding Elections for Senators and Representatives, shall be prescribed in each State by the Legislature thereof; but the Congress may at any time by Law make or alter such Regulations.” Art. I, §4, cl. 1 (emphasis added). Just as the Affordable Care Act directs States to establish Exchanges while allowing the Secretary to establish “such Exchange” as a fallback, the Elections Clause directs state legislatures to prescribe election regulations while allowing Congress to make “such Regulations” as a fallback. Would anybody refer to an election regulation made by Congress as a “regulation prescribed by the state legislature”? Would anybody say that a federal election law and a state election law are in all respects equivalent? Of course not. The word “such” does not help the Court one whit.
And Chief Justice Roberts's response in footnote 2:
The dissent argues that the phrase “such Exchange” does not suggest that State and Federal Exchanges “are in all respects equivalent.” Post, at 8. In support, it quotes the Constitution’s Elections Clause, which makes the state legislature primarily responsible for prescribing election regulations, but allows Congress to “make or alter such Regulations.” Art. I, §4, cl. 1. No one would say that state and federal election regulations are in all respects equivalent, the dissent contends, so we should not say that State and Federal Exchanges are. But the Elections Clause does not precisely define what an election regulation must look like, so Congress can prescribe regulations that differ from what the State would prescribe. The Affordable Care Act does precisely define what an Exchange must look like, however, so a Federal Exchange cannot differ from a State Exchange.