A federal judge on Monday decided to halt an Arkansas law that mandated the display of the Ten Commandments in public school classrooms, barring four of the state’s largest school districts from following the new law, which took effect Tuesday.

U.S. District Judge Timothy Brooks of the Western District of Arkansas issued the preliminary injunction in favor of the lawsuit’s plaintiffs, who argued that the Republican state’s Ten Commandments mandate was unconstitutional because it violated the separation of church and state.

“Why would Arkansas pass an obviously unconstitutional law?” Brooks wrote in the limited ruling. “Most likely because the state is part of a coordinated strategy among several states to inject Christian religious doctrine into public-school classrooms.”

The ruling only applies to four out of 237 school districts in Arkansas.

In April, Gov. Sarah Huckabee Sanders (R-AR) signed the law requiring the Ten Commandments and the words “In God We Trust” to be prominently displayed in public schools and government buildings. The governor’s office has said the law was “entirely appropriate” for students, state employees, and any state resident who enters a building maintained by taxpayer funds.

The plaintiffs maintain the requirement violates parents’ constitutional rights and imposes state-sponsored religious indoctrination onto young, impressionable students.

“Students receiving instruction in algebra, physics, engineering, accounting, computer science, woodworking, fashion design, and German will do so in classrooms that prominently display (the King James version of) the Ten Commandments,” the Obama-appointed judge wrote. “Every day from kindergarten to twelfth grade, children will be confronted with these Commandments—or face civil penalties for missing school.”

The lawsuit was filed by the American Civil Liberties Union, Americans United for the Separation of Church and State, and the Freedom from Religion Foundation.

The ACLU hailed the ruling, with senior staff attorney Heather Weaver declaring, “Public schools are not Sunday schools.”

Attorney General Tim Griffin (R-AR), who has defended the Ten Commandments law against litigation, said he is assessing legal options following the ruling.

Beyond Arkansas, Louisiana, and Texas passed similar laws requiring the biblical text in classrooms. Those measures are also being challenged in court.

The ACLU was one of the plaintiffs that sued to block the Texas law after it was signed by Gov. Greg Abbott (R-TX). A ruling is expected before the law takes effect on Sept. 1.

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In Louisiana, a federal appeals court panel upheld a lower court’s decision and ruled that the state’s law was “facially unconstitutional.” Attorney General Liz Murrill (R-LA) is taking the state’s appeal to the full federal appeals court, where the law was struck down. If that effort fails, Murrill teased that the case could go all the way to the Supreme Court.

The Supreme Court previously ruled on the issue in 1980, when a 5-4 majority decided that Kentucky’s display of the Ten Commandments in public schools was unconstitutional. The justices found the law violated the Establishment Clause of the First Amendment because the display “had no secular legislative purpose” and was “plainly religious in nature.”