A radical election theory has day in court. Justices appear divided.

The U.S. Supreme Court heard oral arguments on Wednesday morning on a case that could have profound effects on the way elections are run in the United States. It is one of the most important and polarizing cases of the current term, and the outcome might – maybe – be a compromise.

Over three hours, the justices probed, challenged, muttered, and at times laughed their way through a case about recent political gerrymandering in North Carolina. Looming over the argument in the case of Moore v. Harper was the phrase that has energized and frightened court watchers in almost equal measure since the court took up the case in June: the independent state legislature theory.

The ISL theory – a fringe interpretation of the U.S. Constitution’s elections clause that has never been endorsed by a court majority – holds that state legislatures have exclusive power to regulate federal elections, free of checks and balances from other branches of state government, like the governor or judiciary. Simply put, Moore asks if a state’s judiciary has the authority to override the state legislature’s redistricting power.

Conservative groups say the theory would be a fairer, more democratic way to draw congressional maps than what happened in North Carolina. (The state Supreme Court there struck down the legislature’s map as an unconstitutional partisan gerrymander and replaced it with its own.)

Critics – a broad and ideologically diverse range of them – counter that state courts shouldn’t be forbidden by the federal courts from interpreting their own state constitutions. Beyond that, they argue that giving state legislatures this authority would transform how federal elections are conducted across the country – creating a two-tier voting system in which rules, procedures, and perhaps even rights vary between state and federal elections.

Wednesday’s argument careened across the legal, historical, and intellectual map – from the English Bill of Rights to antebellum Virginia; from the legal theory of originalism to textualism, then to federalism. Going in, the broad ISL theory had previously been cited approvingly by four conservative justices. Coming out, there seemed a modicum of agreement that state legislatures shouldn’t enjoy unchecked power over setting the rules for federal elections.

What a majority could coalesce around is unclear. But after two existentially fraught election cycles, some of the justices appear wary of throwing another boulder into America’s calming, but still tense, electoral pond.

“This is a proposal that gets rid of the normal checks and balances on the way big governmental decisions are made in this country,” said Justice Elena Kagan. “And you might think that it gets rid of all those checks and balances at exactly the time when they are needed most.”

The meaning of “legislature”

The elections clause of the Constitution states that the “Times, Places and Manner” of holding federal elections “shall be prescribed in each State by the Legislature thereof.” The debate in Moore boils down (in part) to the meaning of the word “Legislature.”

Read to its most extreme, ISL proponents say the word means exactly that: the state’s legislature. Critics argue the word instead means all governmental branches in a state – an interpretation, they note, the high court has upheld numerous times over its history. Past rulings from the court have held that ballot initiatives, gubernatorial vetoes, and independent redistricting commissions are all constitutional under the elections clause.

David Thompson, arguing for the North Carolina legislature, said early on they aren’t saying any of those rulings should be overturned.

We “accept all the court’s precedents,” added Mr. Thompson. “What can’t happen is there can’t be a substantive limitation” by other state actors on how state legislatures manage federal elections.

Much of Wednesday’s argument focused then on what those limitations are, and when federal courts could apply them. Justice Amy Coney Barrett, who appears to be one of the justices likely to be decisive in Moore, said such limitations would be “notoriously difficult lines to draw.”

Justice Brett Kavanaugh also voiced some skepticism, particularly in comparing Mr. Thompson’s ISL arguments with the interpretation the late Chief Justice William Rehnquist offered in a concurrence to Bush v. Gore.

The Rehnquist concurrence “seemed to acknowledge that state courts would have a role interpreting state law, and that federal court review of that should be, in his words, deferential,” said Justice Kavanaugh, who also worked on the case as part of former President George W. Bush’s legal team.

The critics in Moore, he added, “are okay” with that general principle for reviewing state constitutional interpretation, but “your position seems to go further than that.”

Chief Justice John Roberts also appeared skeptical of some of Mr. Thompson’s arguments, but the rest of the court appears evenly divided. The court’s three liberal justices were most critical of the ISL position, questioning not just what limitations courts could impose under this theory, but the fundamentals of the theory itself.

A state legislature “would ordinarily be bound by all of the limitations in the state constitution,” said Justice Ketanji Brown Jackson.

“In the context of the elections clause,” she added, “why do those evaporate?”

The power of state courts

Lawyers for the North Carolina legislature argued that, because state legislative power over federal elections derives from the U.S. Constitution, the state constitution – and thus state courts – should have little influence.

Justices and opposition lawyers nonetheless raised a catalog of issues with the ISL theory – echoing concerns filed in amicus briefs including one signed by the chief justice of every state supreme court in the country. Critics of the ISL theory include some of the most prominent conservative judges and lawyers in the U.S., including the co-founder of the Federalist Society, a prominent Republican former federal appeals court judge, and George W. Bush’s lawyer in the 2000 Florida recount.

“To accept [North Carolina’s] claim, you’d have to ignore the text, history, and structure of our federal Constitution, as well as nearly every state constitution today,” said Neal Katyal, a former acting U.S. solicitor general who represented North Carolina voters and voter advocacy groups.

“They claim the word ‘legislature’ means a species of state law that has literally never existed,” he added. “State lawmaking, unconstrained by a state constitution – that the founders intended to create that animal, surely someone would have said something.”

Instead, experts and briefs describe, most early state constitutions included requirements for how federal elections should be conducted, such as requiring ballots instead of voice votes. The framers, meanwhile, had a well-documented desire for checks and balances throughout U.S. government.

Indeed, in terms of originalism – the judicial philosophy that judges should be bound by the original meaning of the Constitution’s text, which a majority of justices profess to follow – “the more you focus on [it], the weaker the ISL case looks from my vantage point,” said Vikram Amar, dean of the University of Illinois College of Law, on a press call last week organized by the Brennan Center for Justice.

The original meaning of “legislature” in the elections clause “was clear,” according to an amicus brief Dean Amar co-wrote with a pair of constitutional law professors, including Steven Calabresi, a co-founder of the Federalist Society. State legislatures were “created and constrained by the state constitution,” the brief added, and not “independent” in any context.

Most justices on Wednesday didn’t devote time to plumbing historical or originalist arguments over the ISL theory. Instead, they wrestled with that potential compromise – the “notoriously difficult lines” Justice Barrett described.

In that sense, fears leading up to the Moore argument that the court could overnight plunge America’s electoral system into chaos and confusion have been somewhat assuaged. Setting aside disagreements over text, history, and original meaning, there was some agreement that federal courts could impose new standards on state courts adjudicating gerrymandering claims, without revoking state courts’ judicial review power entirely.

Whether a majority of justices are able to find an agreement like that remains to be seen. But on the press call last week, Eliza Sweren-Becker, counsel in the Democracy Program at the Brennan Center, said even a compromise ruling would be “unprincipled” and “result in chaos.”

Anything short of rejecting the ISL theory wholesale, she added, “asks the court to do something that the court has never done before, that flies in the face of history, that flies in the face of practice.”

Michael McConnell, a professor at Stanford Law School and a former federal appeals court judge, isn’t so sure.

He agrees that state legislatures, created and bound by their state constitutions, can’t be “independent” when it comes to federal elections. But he thinks the specific reference to “legislatures” in the elections clause means they should be given some special authority over federal elections.

“The most plausible, the most convincing, and also the most practical way to put those oppositions together,” he says, is to say “the legislature has to do the actual districting, but it’s subject to standard judicial review.”

“In the current hyper-partisan environment,” he adds, the parties and the amici “are all adopting one extreme position [or] the other, instead of looking for a middle-ground interpretation.”