In early June, a state board in Oklahoma did something that seemed obviously unconstitutional: It approved a new, openly Catholic charter school. Students at the proposed St. Isidore of Seville Catholic Virtual School would receive religious instruction, and the online school would participate in “the evangelizing mission of the Church,” according to St. Isidore’s application to the state. By law in Oklahoma, and in every state where charter schools are allowed, charters are public schools—they receive government funding and some state oversight, and they cannot discriminate against students and staff. St. Isidore would apparently be public, too, raising questions about whether it violates the First Amendment’s separation of church and state.

If St. Isidore opens next year as planned, it would represent a profound shift in American education, and could potentially allow for religious charters to open across the country. It would also represent a remarkable change for the charter-school movement itself, which has long tried to rally support for charters on the grounds that they are public.

In the three decades that charter schools have existed, some have opened with an emphasis on, say, “classical” values or Hebrew language and culture, but none has been explicitly religious. And though the charter movement has always had broad appeal on the left and right, including from skeptics of public education and people who believe that charters introduce healthy competition into the public sector, supporters have generally agreed that charters should be secular. Now new players such as the Archdiocese of Oklahoma City are pushing the movement in a radically different direction, arguing that charter schools can offer religious education.

Some longtime advocates of charter schools fear that such a dramatic shift could threaten support for charters at a time when many prominent Democratic leaders, including President Joe Biden, have become more critical of them. “This is probably the biggest challenge to the intent and origins of chartering that I’ve seen in 30-plus years,” Ember Reichgott Junge, a former Democratic state senator who wrote the country’s first charter-school law, in Minnesota, told me.

[From the January/February 2018 issue: The charter-school crusader]

How did the movement get to this point? The story is complicated, often intertwined with the school-voucher movement, and still evolving. A group of parents and clergy, represented by organizations such as the ACLU and Americans United for Separation of Church and State, has already filed a lawsuit to stop St. Isidore from opening, moving the issue into the court system. If the Supreme Court takes up the case, the justices will have to consider, and could finally resolve, a bigger question that underlies the debate over St. Isidore: Are charters truly public?

When Minnesota passed the country’s first charter-school law in 1991, early supporters pitched charters as a new type of public school, one paid for largely with tax dollars but free of the control of local school districts. Reichgott Junge believed that charters would spur innovation within the public-school system. Ted Kolderie, a political theorist who also was involved in the law’s passage and later promoted the concept across the country, described charter schools as a “second sector” of public education. In California, which passed its own charter-school law the next year, Democratic State Senator Gary K. Hart argued that charter schools represented “a major education reform” that would provide families with more choices “while maintaining our traditional democratic commitment to public schools.”

Minnesota’s statewide teachers’ union, however, warned that charters would create an “additional, untested, competing system.” Some educators viewed charter schools as a disguised form of school-voucher programs, which allow families to use tax dollars to pay for private education. Just one year earlier, Milwaukee had started the country’s first modern voucher program. Albert Shanker, then the president of the American Federation of Teachers, briefly supported charters before lumping them in with vouchers as a “gimmick” that would do little to improve public education.

Despite those early objections, charter schools soon spread from Minnesota to much of the rest of the country with support from both Democrats and Republicans. In some cases, charter schools were offered up as a less controversial alternative to vouchers. Milwaukee’s school-voucher program and one in Cleveland, the first two in the country, were caught up in court battles for years over the participation of private religious schools. (Milwaukee’s voucher program started with secular private schools before it expanded to include religious ones, while Cleveland’s included sectarian schools from the beginning.)

Still, charter schools raised some legal questions of their own. In one early lawsuit from 1994, members of Michigan’s state board of education, backed by teachers’ unions, challenged the constitutionality of the state’s new charter schools. “The legislature does not have the right to define public schools in any way it desires,” one of the lawyers in the case charged. Eventually, the Michigan Supreme Court upheld the law and declared charters to be public.

Charter schools survived such early legal challenges and thrived over the following years, far outpacing school vouchers in popularity in state legislatures—in part, because they were secular and subject to some of the same accountability requirements as traditional public schools. As of 2021, charters served about 3.7 million students, or roughly 7 percent of America’s public-school students. The latest study from the Stanford University–based Center for Research on Education Outcomes found that charter schools have a slight edge over traditional public schools in test scores. The difference, however, was quite small, and some past studies have found that the effect of charters varies widely from school to school.

The idea of a religious charter school started percolating among some school-choice advocates after a 2002 Supreme Court case related to school vouchers. In Zelman v. Simmons-Harris, the Court ruled 5–4 that Cleveland’s voucher program didn’t violate the First Amendment’s separation of Church and state because of the role that parents played in directing where the public dollars were spent. Chester E. Finn Jr., then the president of the right-leaning Fordham Institute, published an article arguing that the case had done more than validate vouchers: It also raised the possibility of religious charter schools. Much like vouchers, he pointed out, charters rely on parental choice; a charter school doesn’t receive state funding unless parents choose to enroll their children there.

[Adam Laats: The Supreme Court has ushered in a new era of religion at school]

Finn’s argument didn’t gain much traction at the time—Reichgott Junge called it an “outlier view.” Many Democratic charter-school supporters were leery of being lumped together with supporters of vouchers, and religious charters still seemed like a stretch legally. In 2007, Lawrence Weinberg, a lawyer, and Bruce Cooper, an education professor, defended the idea of an emerging middle ground: In some states, an organization could be allowed to run a charter school that reflected the culture of a particular religion but did not “endorse the tenets of the faith,” as Weinberg and Cooper put it. The Ben Gamla Charter School in South Florida, for instance, soon offered students a curriculum focused on Hebrew language and history. Other charter schools opened with a focus on Arabic, Hmong language and culture, and Greek language. Some financially strapped Catholic schools, too, chose to convert to charters rather than close, keeping certain aspects of Catholic education while eliminating prayer and religious instruction.

Two more recent Supreme Court cases have emboldened some advocates interested in greater state aid for private education. In 2020, the Court’s conservative majority ruled in Espinoza v. Montana Department of Revenue that Montana couldn’t exclude religious private schools from participating in a voucherlike program that included nonreligious private schools; two years later, in Carson v. Makin, the Court ruled that private religious schools must receive public benefits offered to other private schools. In both cases, Chief Justice John Roberts framed the issue as one of religious discrimination. In his dissent in Espinoza, now-retired Justice Stephen Breyer suggested that the majority opinion could have broader implications: “What about charter schools?” he asked.

To some advocates of religious charters, the answer was that charter schools shouldn’t be considered public—and that state laws prohibiting religious charters were likely unconstitutional. After the Espinoza case, Nicole Stelle Garnett, a law professor at Notre Dame, argued in a widely read report for the right-leaning Manhattan Institute that, in most states, charter schools aren’t “state actors,” or entities acting on behalf of the government, even though they receive government funding. That means that most charters are “effectively private schools and can be religious,” she wrote. “And if they can be religious, states with charter schools must permit religious charter schools.”

The “state actor” argument has already been litigated in one recent case, though that doesn’t end the issue. In North Carolina, a self-described “classical” charter required girls to wear skirts as part of its emphasis on traditional values and “chivalry,” in the words of its founder, who also referred to women as “fragile vessel[s]” who should be honored by men. Parents, backed by the ACLU, sued the school for sex discrimination. School officials argued that charters aren’t state actors and shouldn’t be subject to federal antidiscrimination laws. But a federal appeals court ruled last year for the parents, and the Supreme Court declined to take the case.

In Oklahoma, St. Isidore’s backers, including Republican Governor Kevin Stitt, are seeking to challenge their state’s existing ban on religious charters. In their application, officials from the Archdiocese of Oklahoma City argued both that charter schools are not state actors and that Oklahoma’s existing charter statutes are unconstitutional because they discriminate against religious organizations. “The pertinent question … is not whether Oklahoma’s charter school statute purports to ban religious charter schools. The question is whether it would be lawful … to actually enforce such a prohibition,” the application said. “The answer to that question is no.”

The lawsuit attempting to stop St. Isidore from opening, filed in state court in July, argues that charters, as public schools, must remain secular. “Schools that do not adhere to this principle have long existed and are entitled to operate,” the suit reads, “but they cannot be part of the public-education system.” It also alleges that St. Isidore—whose application says it will operate “in harmony with faith and morals, including sexual morality” of the Catholic church—could discriminate based on religion, sexual orientation, and gender identity. St. Isidore has said it will comply with state and federal law but could seek religious exemptions based on Catholic belief.

As the concept of religious charter schools continues to get tested in court, a divide has opened up within the charter movement. Many prominent charter supporters, including the earliest advocates, maintain that charters are public and strongly oppose religious charters. Among them is Nina Rees, the president of the National Alliance for Public Charter Schools and a former George W. Bush administration official. Reichgott Junge, who championed Minnesota’s original charter law, has helped create the National Charter Schools Founders Library to preserve the original history of the charter-school movement, including interviews with key figures and archival documents—an effort she believes could be instrumental in showing in future court cases that charter schools were always envisioned as public entities.

[Jonathan Merritt: Teaching the Bible in public schools is a bad idea—for Christians]

If a state’s charter schools begin to deliver religious curriculum, Reichgott Junge told me, those schools “should not be called ‘charters.’ They should be called something else. We’d have to find another name for them.”

Andy Smarick, a senior fellow at the Manhattan Institute, recently suggested that liberal charter-school backers should consider supporting religious charters as a way to keep families “engaged with the public school system.” Religious charter schools should be allowed to operate as public schools, he has written, if they do not discriminate against prospective students and if they “follow public rules related to finances, operations, safety, and achievement.” But others on the right have urged more caution around religious charters. Matthew Ladner, a senior adviser at the right-leaning Heritage Foundation, referred to religious charter schools as legally “permissible” but ultimately a bad idea because of the potential for excessive state regulation.

Finn, who raised the idea of religious charters 20 years ago, told me recently that he still favors the concept. In his view, charter schools are akin to “private operators under contract to the state to provide education services”—not public entities themselves. “But I understand the symbolism of ‘public education’ and why most of the charter world is far more comfortable (and more politically secure) under that umbrella,” he wrote in an email.

Backed by the Supreme Court, the school-choice movement has seen success after success. New charter operators are likely to test religious schools in other states, perhaps forcing the Supreme Court to finally clarify how charters fit into America’s educational landscape. Given the Court’s current makeup, it’s very possible that St. Isidore in Oklahoma could represent the future of charter schools—a future never envisioned by their early advocates.

This article has been adapted from Fitzpatrick’s book, The Death of Public School: How Conservatives Won the War Over Education in America.