A ruling for St. Isidore would have allowed, for the first time, direct and complete taxpayer funding to establish a faith-based charter school, legalizing government sponsorship of a curriculum that calls for students to adhere to Catholic beliefs and the church’s religious mission.

Instead, the current landscape of government funding for religious schools remains intact. Under previous court rulings, taxpayer money may be used for vouchers to pay tuition at religious schools. But public schools — including charter schools — may not include religious teachings, because they are established and completely funded by the government.

The deadlock did not amount to a legal decision on the issue. Still, Yale Law School professor Justin Driver, an expert on education law, noted that the outcome was a departure from recent court rulings under Chief Justice John G. Roberts Jr. that have given religion a larger role in public life.

“The Roberts Court has been extremely solicitous of free exercise claims over the years, and this one did not prevail,” Driver said, referring to the Constitution’s protection of the right to practice religion. “I view this as a really significant decision, and I’m sure there are many people in the education world who … view it as a bullet dodged.”

Justice Amy Coney Barrett’s decision not to participate in the Oklahoma case created the conditions for a deadlocked court. Barrett did not explain her recusal, but it probably stemmed from her close ties to Notre Dame Law School and its religious liberties legal clinic, which played a prominent role in representing St. Isidore.

While it is impossible to know how Barrett would have voted, Driver said he thinks a religious charter school could prevail in a case with a different plaintiff and all nine justices participating: “One could imagine this case returning, and assuming no changes on the court, it being decided by a 5-4 decision.”

Advocates of increased public funding for religious education have spent years laying the groundwork for such legal challenges. Notre Dame Law School professor Nicole Garnett, who helped spearhead the push to create St. Isidore, said Thursday’s outcome was not what she expected.

“I’m obviously very disappointed, and after argument, surprised,” Garnett said in an email. “But there is no precedential value to this order so the issue remains a live one.”

The deadlock came as a relief to opponents who say religious public charters blatantly violate the separation of church and state and could discriminate against religious minorities, nonbelievers and gay people.

“This court has demonstrated a hostility to the separation between church and state in recent years, but a case like this was a bridge too far even for this court,” said Daniel Mach, director of the ACLU’s Program on Freedom of Religion and Belief. “The Supreme Court’s ruling affirms that a religious school can’t be a public school and a public school can’t be religious.”

The ACLU and Americans United for Separation of Church and State had filed a lawsuit in Oklahoma seeking to block the creation of St. Isidore, but it was a different lawsuit — one filed by the Oklahoma attorney general — that ended up before the high court.

The outcome was also welcome news for many charter school advocates, who fear that allowing religious charters would upend the legislative and political support for their model in some states. Starlee Coleman, president of the National Alliance for Public Charter Schools, said the opinion “sends an important message: public charter schools are just that, public.”

Gregory Garre, the lawyer for Oklahoma Attorney General Gentner Drummond (R), praised the justices for “leaving intact the charter school laws in Oklahoma and across the country.”

The court’s unsigned, one-sentence order did not include a vote count, saying only that the judgment of the Oklahoma court is “affirmed by an equally divided Court.”

At oral argument in April, all three liberal justices expressed deep skepticism about a religious charter school.

Roberts, a conservative who is almost always in the majority in the court’s most significant cases, has consistently sided with religious parties to expand the role of faith in public life. In this case, he asked probing questions of both sides,referring to past high court decisions that allowed publicly funded vouchers and playground improvements for parochial schools.

Of St. Isidore, the chief justice said: “I mean, this does strike me as a much more comprehensive involvement.”

Neal McCluskey, director of the Cato Institute’s Center for Educational Freedom, said based on those comments, Roberts was probably the swing vote. “While we do not know which justices voted for or against the Catholic charter school, Chief Justice Roberts indicated early on in oral argument that he saw religious charter schooling as more complex than school choice programs that allow families to use public funds at private schools,” he said.

The Archdiocese of Oklahoma City and the Diocese of Tulsa sought to establish St. Isidore’s as an online-only school that would initially educate several hundred students in kindergarten through 12th grade. The school would have served students with special needs and those in rural Oklahoma who do not have access to brick-and-mortar religious schools.

St. Isidore would have been open to students of all faiths and abided by state antidiscrimination rules, according to its founding documents. But school materials say that “admission assumes the student and family willingness to adhere with respect to the beliefs, expectations, policies, and procedures of the school.”

The case landed at the high court after a contentious fight that divided Republicans in Oklahoma, one of the nation’s most conservative states, and stirred vigorous objections from liberals and some parents.

Catholic officials first floated the idea for the school in 2021; it was narrowly approved by the state’s virtual charter board in 2023. Groups opposed promptly sued, saying their tax dollars should not be used to bolster religious views that many did not share.

Drummond, the Oklahoma attorney general, then filed his own suit, arguing the charter board’s contract with St. Isidore violated the state’s constitution. The Oklahoma Supreme Court sided with Drummond, and the contract was rescinded.

Advocates for religious education were hopeful the justices would side with them after a string of recent decisions that have gradually increased religious liberty while shrinking the divide between church and state. In 2022, for instance, the justices ruled a school district infringed on the religious freedoms of a high school coach by disciplining him for praying on a football field.

James A. Campbell, an attorney for the charter board that approved St. Isidore’s application, told the justices during oral argument in April that not allowing public funding of the school amounts to religious discrimination. He said the state funds language-immersion schools and schools centered on Native American culture, but “there’s one type of education that’s off limits, and that’s religion.”

“That can’t be consistent with this court’s precedent,” Campbell said.

But Garre, the Oklahoma lawyer who argued before the high court, urged the justices to rule against St. Isidore, also citing precedent.

A decision in favor of the school “would result in the astounding rule that states not only may, but must fund and create public religious schools,” Garre said, calling the notion “an astounding reversal from this court’s time-honored precedents.”

Such a ruling would have had unpredictable but sweeping consequences.

On one hand, many expected a green light for religious charter schools to quickly transform the educational landscape in many states, with religious schools converting to charter school status to take advantage of public funding. Some existing charter schools could have incorporated religion into their programs.

At the same time, experts in the field worried that a decision allowing religious charter schools could have negatively affected the funding systems and political support that enables all charter schools. For instance, states currently provide funding through the per-pupil formula available only to public schools. If the Supreme Court declared that charter schools were actually not public schools, that might have jeopardized their funding, advocates said.

The Supreme Court is set to issue a number of other high-profile rulings as the term nears it end. In another case dealing with religion, the court is set to decidewhether Wisconsin can strip tax exemptions that Catholic Charities and other religious institutions receive.