The following is a guest post from Carolyn Shapiro:

As others have already noted, the Supreme Court’s opinion in Moore v. Harper fortunately eliminated the most chaotic possible outcome and reiterated what has always been understood to be true — state legislatures are subject to the constraints of state constitutions and the oversight of state courts when they regulate federal elections. But as also been noted, the Court did not eliminate the possibility of federal court oversight of decisions made by state courts construing and applying their own constitutions and statutes. Nor did the Court provide much insight into what standard would apply to determining when a state court has gone too far.

This aspect of the decision means that uncertainty and lack of clarity persist, but I don’t think that any of us should be surprised. It was, in my view, implausible that the Court would disavow any role for federal judicial oversight of state court decisions involving federal elections, nor do I think that it should have. And while I would have preferred the Court to use narrower language, I think that the majority’s invocation of Justice Souter’s Bush v. Gore opinion is somewhat reassuring. In that opinion, Justice Souter stated expressly that disagreement over the interpretation of a statute is well within the bounds of ordinary judicial review and thus should not give rise to federal judicial intervention.

But I want to elaborate on the suggestion by Derek Muller and Ned Foley that the opinion puts “state courts on notice,” and in particular respond to Ned’s argument that what state courts should now know that they can’t do is “judicial alteration of an unambiguous state legislative rule, based on nothing more than a vague provision of a state constitution unambiguous statutory language” the way, he says, the Pennsylvania Supreme Court did in 2020.

I disagree with Ned’s characterization of what the Pennsylvania Supreme Court did in 2020 as an obvious overreach, and I think that if state courts (and the Supreme Court) follow this path, it could have consequences for the development of state law. Explaining that requires a bit of a deep dive into the Pennsylvania opinion and the history of the relevant statute, which I discuss in detail in my article on the ISLT in the University of Chicago Law Review and will summarize here.

When Pennsylvania revamped its election law in 2019, before COVID, it significantly expanded mail-in voting for the first time, which Democrats wanted, and it eliminated straight-ticket voting, which Republicans wanted. As far as I have been able to determine, the election-day deadline for the return of mail-in ballots was not a point of contention. But by the fall of 2020, the facts on the ground had changed in two important ways. First, there was COVID. And second, the United States Postal Service announced that it could not guarantee that mail-in or absentee ballots would be delivered to assure compliance with statutory deadlines.

As I explained in my article:

In the run-up to the November 2020 election, the Pennsylvania Supreme Court unanimously agreed that voters who voted by mail, complying with all statutory requirements, faced a realistic danger that their mail-in ballots would not be received by election officials in time, given the particular circumstances of the election. … All seven justices also concluded that, as a result, the statutory schedule for application and return of mail-in ballots would disenfranchise voters and was inconsistent with the state constitution’s guarantee of free and fair elections, that judicial relief was therefore necessary, and that appropriate relief required modifying one of the statute’s deadlines for the 2020 general election only. They disagreed, however, about which deadline should be modified. A four-justice majority exercised the court’s equitable powers and extended the deadline for receipt of absentee ballots. The three dissenting justices would have instead moved the deadline to apply for a ballot, making it earlier, but would have similarly expanded the time period between the application deadline and the ballot-receipt deadline.

So, what should the Pennsylvania Supreme Court have done? The court believed – unanimously – that the unambiguous statute could not operate constitutionally under its “free and fair elections” clause. But either form of equitable relief under consideration – extending the received-by deadline or making the application deadline earlier – would have rewritten an unambiguous statute. Under Ned’s view, I think, the court should have done nothing, at least with respect to federal elections. But unless it issued one ruling for state elections and another for federal elections – which creates its own obvious and significant problems – the result would be that the threat of Supreme Court review under the Elections and Electors Clauses would stymie the application and development of state constitutional law. The free and fair elections clause may be vague, but like all vague constitutional provisions, it can take on meaning through judicial decisions. It seems to me that we should want that kind of judicial development, not discourage it.

In the end, I agree that state courts are “on notice,” but I take a different view of what that notice means, or should mean, than does Ned. In my view, state courts should be as meticulous and explicit as possible about how whatever they are doing is consistent with their state’s precedent, practice, statutes, and constitution. (Derek suggests something similar.) In a state where the legislature itself has instructed the courts to engage in purposive statutory interpretation, for example, or where longstanding precedent has established that approach, the state court should spell all of that out. There are a variety of ways that the Pennsylvania Supreme Court could have better defended and explained its opinion, which I discuss in my article. And as Michael Weingartner and I argue, due process principles, focusing on reliance interests, better apply here than some sui generis Elections and Electors Clause analysis that asks how far a state court, with its own unique legal culture, constitution, and precedent, has strayed from some unknowable baseline.