Gov. Jeff Landry signed legislation on Wednesday requiring the display of the Ten Commandments in every public classroom in Louisiana, making the state the only one with such a mandate and reigniting the debate over how porous the boundary between church and state should be.
Critics, including the American Civil Liberties Union and the Freedom From Religion Foundation, vowed a legal fight against the law they deemed “blatantly unconstitutional.” But it is a battle that proponents are prepared, and in many ways, eager, to take on.
“I can’t wait to be sued,” Mr. Landry said on Saturday at a Republican fund-raiser in Nashville, according to The Tennessean. And on Wednesday, as he signed the measure, he argued that the Ten Commandments contained valuable lessons for students.
“If you want to respect the rule of law,” he said, “you’ve got to start from the original law giver, which was Moses.”
The legislation is part of a broader campaign by conservative Christian groups to amplify public expressions of faith, and provoke lawsuits that could reach the Supreme Court, where they expect a friendlier reception than in years past. That presumption is rooted in recent rulings, particularly one in 2022 in which the court sided with a high school football coach who argued that he had a constitutional right to pray at the 50-yard line after his team’s games.
“The climate is certainly better,” said Charles C. Haynes, a senior fellow at the Freedom Forum and a scholar with an expertise in religious liberty and civil discourse, referring to the viewpoint of those who support the legislation.
Still, Mr. Haynes said that he found the enthusiasm behind the Louisiana law and other efforts unwarranted. “I think they are overreaching,” he said, adding that “even this court will have a hard time justifying” what lawmakers have conceived.
The measure in Louisiana requires that the commandments be displayed in each classroom of every public elementary, middle and high school, as well as public college classrooms. The posters must be no smaller than 11 by 14 inches and the commandments must be “the central focus of the poster” and “in a large, easily readable font.”
It will also include a three-paragraph statement asserting that the Ten Commandments were a “prominent part of American public education for almost three centuries.”
That reflects the contention by supporters that the Ten Commandments are not purely a religious text but also a historical document, arguing that the instructions handed down by God to Moses in the Book of Exodus are a major influence on United States law.
“The Ten Commandments is there, time and time again, as the basis and foundation for the system that America was built upon,” said Matt Krause, a lawyer for the First Liberty Institute, a nonprofit legal organization defending religious expression.
Still, as lawmakers debated the measure, its supporters argued that such a visible display was about more that just sharing legal history.
“Given all the junk our children are exposed to in classrooms today, it is imperative that we put the Ten Commandments back in a prominent position,” said State Representative Dodie Horton, the Republican sponsor of the legislation.
The measure allows for “our children to look up and see what God says is right and what he says is wrong,” Ms. Horton told colleagues. “It doesn’t preach a certain religion, but it definitely shows what a moral code we all should live by is.”
Critics said the legislation was a clear constitutional violation. In a joint statement, groups including the American Civil Liberties Union of Louisiana, Americans United for Separation of Church and State and the Southern Poverty Law Center argued that the law “violates students’ and families’ fundamental right to religious freedom.”
“Our public schools are not Sunday schools,” the statement said, “and students of all faiths, or no faith, should feel welcome in them.”
The law is a product of a legislative season in which Republican lawmakers who had felt stifled for eight years under a Democratic governor, John Bel Edwards, sought to advance a flurry of conservative legislation to Mr. Landry, his Republican successor.
In a special session this year, lawmakers rolled back a previous overhaul of the criminal justice system and passed bills to lengthen sentences for some offenses, strictly limit access to parole, prosecute 17-year-olds charged with any crime as adults and allow methods of execution beyond lethal injection.
Lawmakers also advanced first-in-the-nation measures like designating abortion pills as dangerous controlled substances and allowing judges to order surgical castration of child sex offenders.
Louisiana is the first state to enact a requirement for displaying the Ten Commandments in schools since the Supreme Court struck down a Kentucky law in 1980 that had a similar directive. In that case, Stone v. Graham, the court found that the law violated the establishment clause of the First Amendment.
But the Supreme Court has become more likely to rule in favor of religious rights under Chief Justice John G. Roberts Jr.
Perhaps the strongest signal, conservative lawyers and activists said, was the 2022 ruling that found that Joseph Kennedy, an assistant football coach at a public high school near Seattle, was protected by the First Amendment when he offered prayers after games, often joined by students.
With that ruling, the majority discarded a longstanding precedent known as the Lemon test, which was applied to cases related to the establishment clause of the First Amendment. The clause is intended to “prevent government from either advancing (that is, establishing) or hindering religion, preferring one religion over others, or favoring religion over nonreligion,” Mr. Haynes wrote.
The test required courts to consider whether the government practice being challenged had a secular purpose, whether its primary effect was to advance or inhibit religion, and whether it encouraged excessive government entanglement with religion.
The ruling was “kind of an inflection point,” Mr. Krause said, adding, “I think that any decision that was based solely on the Lemon test is open to new scrutiny, whether that was graduation prayers or Nativity scenes on public lands or the Ten Commandments.”
The Louisiana legislation — and the litigation it essentially guarantees — provides an opportunity to apply that scrutiny to public displays of the Ten Commandments.
Legislative efforts in other states have had a bumpy path. Similar proposals failed recently in Mississippi, Oklahoma, South Carolina and Texas. One introduced in Utah this year was watered down to a measure that would add the Ten Commandments to a list of documents and principles that could be included in school curriculums.
Mr. Haynes of the Freedom Forum said he believed that the courts — including the Supreme Court, if the cases ascends that high — would see through the statements about historical context and recognize that the motivation was to inject religious teaching into public classrooms.
If the courts did not agree, he said, the result would amount to a catastrophic erosion in the divisions between government and religion.
“That would change who we are as a country, to go in that direction and have no barrier to government entanglement with religion,” Mr. Haynes said. “What would be left? What couldn’t the government do?”
Michael Levenson and Sarah Mervosh contributed reporting.
