As briefing nears its close, the battle lines are emerging in Moore v. Harper – the case in which the Supreme Court will consider whether to adopt some form of the independent state legislature (ISL) theory. As a refresher, the ISL theory contends that state legislatures may regulate federal elections free of any checks by other state-level actors. So, under the theory, no state constitutional provisions, no state court, and potentially no governor’s veto could constrain a state legislature’s exercise of power over federal elections.

In Moore v. Harper, members of the North Carolina state legislature (the petitioners) are invoking the ISL theory to claim that the North Carolina state courts violated the federal constitution when they found congressional maps drawn by the legislature to violate the state constitution. The respondents include the state of North Carolina, as well as the individual voters and non-partisan voting rights and democracy organizations that brought the state court suits challenging the maps. Few significant cases before the Supreme Court in recent memory have seen such a broad coalition from across the political spectrum come together on one side – in this case, against the independent state legislature theory.

Now that the (more than 40) briefs are mostly in – the petitioners are likely to file a reply in the next few weeks – three key themes are worth keeping an eye on as the case barrels towards oral argument on Dec. 7. (As a point of disclosure, I represented Professor Evan Bernick, an originalism scholar, in a brief supporting the respondents.)

Conservatives are lining up to urge the Court to reject the ISL theory.

Since the Supreme Court took the case in June, the respondents have added the revered retired conservative court of appeals judge J. Michael Luttig to their counsel team. Luttig, once shortlisted for a Supreme Court seat by the George W. Bush White House, mentored many of the conservative legal elite as his law clerks, including Senator Ted Cruz, Trump-era Solicitor General Noel Francisco, FBI Director Christopher Wray, and John Eastman.

Now that amicus briefs are in, the respondents have the support of several retired four-star military officers, two Federalist Society co-founders, multiple retired conservative court of appeals judges, a longtime Republican election lawyer, a Reagan-era Solicitor General, multiple Republican former state secretaries of state, multiple Republican former governors, civil rights and good government groups, and a chorus of highly-respected and ideologically diverse historians and legal scholars. And, the Conference of Chief Justices, representing all 50 state supreme court justices, filed a brief squarely rejecting the notion that state courts and state constitutions cannot check state legislatures when they regulate federal elections.

Supporting the petitioners? John Eastman, a bevy of beltway think tanks, and a smattering of red state Attorneys General and other state elected officials, none of whom oversee elections. No historians, no legal scholars, and no election officials showed up in support of the ISL theory.

Despite the United States’ extremely polarized politics, the sheer number of conservatives joining liberals and non-partisan groups to reject the theory should not be so surprising here. Defending checks and balances is not partisan: An unconstrained state legislature might benefit republicans in Ohio and bowl them over in New York. Or it might help Democrats in 2022, but not in 2032. As this broad coalition of amici recognize, the checks and balances enshrined in both federal and state constitutions protect the people against abuses of power, no matter how the political wind might be blowing in a given moment.

Amici of all political leanings confirm the devastating consequences of adopting the ISL theory on U.S. elections.

In their opening brief, the petitioners largely sidestepped the ISL theory’s sweeping consequences for the electoral system, instead characterizing the theory as legally-mandated, no matter the consequences. The respondents, by contrast, explained that the theory would upend election administration in three ways. First, as the petitioners agree, it would nullify some or all state constitutional provisions for federal elections, dramatically changing the rules governing elections, no matter how sound or longstanding. Second, it would do so only for federal elections, thus creating a two-track system of election administration that would be nearly impossible either for officials to administer or for voters to understand. And, third, it would inject massive uncertainty about the remaining powers, if any, of both state courts and state executive officials regarding federal elections. Confirming that the respondents’ arguments are neither unwarranted anxiety nor academic speculation, amici with real-world election and judicial experience from across the political spectrum have echoed these same concerns.

On the first point, the non-partisan Brennan Center for Justice detailed how the ISL theory would nullify or undermine hundreds of state constitutional provisions and related state court decisions and would threaten a host of election rules enacted via ballot initiatives. Agreeing entirely, prominent Republican election lawyer Ben Ginsberg called the petitioners’ ISL theory a “potential voter confusion disaster” and a mess for election officials as they would struggle to determine which rules were and were not still valid. And, as Ginsberg, a number of Republican former elected and executive branch officials and multiple briefs from bi-partisan groups of election administrators, warned, the ISL theory would usher in a two-track system of election law and make “state and federal elections practically impossible to administer.”

Multiple amicus briefs, including a brief on behalf of nearly a dozen prominent conservatives – among them multiple former elected officials and retired D.C. Circuit Judge Thomas Griffith and Bush-era Acting Attorney General Peter Keisler (also a co-founder of the Federalist Society) – and the brief from the Conference of Chief Justices, agreed and all warned that adopting the ISL theory would lead to a flood of potentially destabilizing election-related litigation in federal courts. Giving federal courts the last word on the meaning of state election law potentially transforms every election-related question of statutory interpretation into a federal lawsuit. Transferring that much power from state actors to the federal courts presents, in the words of the Chief Justice of the Texas Supreme Court, “the biggest federalism issue in a long time.”

In short, the ISL theory, if adopted, would create what Ginsberg called a “toxic brew of uncertainty, distrust, partisanship and unchecked power” that could lead to a number of election “nightmare scenarios.” And those “nightmare scenarios,” a group of retired four-star admirals and generals and former service secretaries explained, could be devastating to national security.

The historical debate over the ISL theory looms large at the Court, but is settled (and rejected) within the academy.

All sides agree that the ratifying public’s understanding of the Elections Clause is going to be the front and center legal question in this case. That is, after all, how a majority of this Supreme Court purports to interpret the Constitution.

So, how does the ISL theory square with the original understanding of the Elections Clause? As Vikram Amar, Akhil Amar, and Stephen Calabresi (a co-Founder of the Federalist Society) put it in their striking brief: “Miserably.” Echoing what I and others have written elsewhere in the popular press, leading academic historians and constitutional law scholars all told the court the same thing: The Founding-era evidence plainly shows that state legislatures are bound by their state constitutions when regulating federal elections. Indeed, early state constitutions were littered with provisions regulating federal elections, which were understood to be enforceable by state courts.

The petitioners had no law professors or historians in their ranks of amici. Instead, in their own brief, they relied heavily on a document called the “Pinckney Plan,” which purports to be an early draft of the Constitution. That draft, they claim, shows that the Constitution’s drafters explicitly rejected a plan that would assign power to “States” and instead gave them to “legislatures”–bolstering their claim that the legislature must therefore have some unique and unconstrained power in this arena.

But, as both the respondents and amici showed, the Pinckney Plan is a fraudulent document, forged by Charles Pinckney to aggrandize his role in the Constitution’s drafting. In the Amar amici’s words, the ISL theory’s best evidence is a “bogus document.” To be clear, the petitioners and others before them have in all likelihood relied on the Pinckney Plan in good faith. But that they, too, were duped shows the value of deciding complex and consequential topics only after full briefing and amicus participation. As the Amars and Calabresi put it: “Petitioners are not expert historians–alas, not even competent ones. . . . Proper originalism is serious business and the Court needs to hear from serious scholars.”

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The independent state legislature theory’s emergence has largely taken place in an emergency posture. That means that, in previous cases, neither courts nor the public had the benefit of time for the parties–let alone historians and legal scholars, election administrators and elected officials–to weigh in on either the historical basis for or effect of removing essential checks and balances on state legislatures when they act in the most partisan of arenas. In this hugely consequential case, in a highly polarized environment, experts of all stripes and partisan affiliations have now weighed in with roughly the same answer: Giving state legislatures unchecked power over federal elections is both antithetical and dangerous to the U.S. constitutional order.

IMAGE: Voters fill out and cast their ballots at the early voting location at White Oak Community Recreation Center on October 27, 2022 in Silver Spring, Maryland. Including this location in Silver Spring, Montgomery County opened 14 early voting sites on Thursday that will remain open through November 3. (Photo by Chip Somodevilla/Getty Images)