ACLU sues Louisiana over requiring the display of Ten Commandments in public schools

US civil liberties groups have sued Louisiana for what they called its “blatantly unconstitutional” new law requiring all state-funded schools to display the Ten Commandments in classrooms.

The American Civil Liberties Union (ACLU) joined with its Louisiana affiliate and two other bodies – Americans United for Separation of Church and State and the Freedom from Religion Foundation – for the suit against the law, signed on Wednesday by the state’s rightwing Republican governor, Jeff Landry.

Related: Ten Commandments to be displayed in Louisiana public school classrooms

Landry, who succeeded the former Democratic governor John Bel Edwards in January, provocatively declared after signing the statute: “I can’t wait to be sued.”

The four groups immediately took him up on his challenge by announcing they were doing precisely that.

“We’re suing Louisiana for requiring all public schools to display the Ten Commandments in every classroom,” the ACLU posted on X (formerly Twitter). “Public schools are not Sunday schools.”

In a joint statement, the ACLU and its allies said the law, HB 71, amounted to religious coercion. They also said it violated Louisiana state law, longstanding precedent established by the US supreme court and the first amendment of the US constitution, which guarantees separation of church and state.

“The first amendment promises that we all get to decide for ourselves what religious beliefs, if any, to hold and practice, without pressure from the government. Politicians have no business imposing their preferred religious doctrine on students and families in public schools,” the statement said.

“Louisiana’s communities and public schools are religiously diverse, yet HB 71 would require school officials to promote specific religious beliefs to which people of many faiths, and those of no faith, do not subscribe.”

The legislation mandates that an 11-by-14in poster of the Ten Commandments must be displayed prominently in classrooms of all state-funded educational institutions, from kindergarten up to university, by 2025. No state funding is being offered to comply with the initiative.

A four-paragraph “context statement” is to be shown beside the document describing how the biblical strictures “were a prominent part of the American public education for almost three centuries”.

Critics point out that the wording of the Ten Commandments vary within different branches of Christianity and that they are also a central part of Judaism. The Louisiana legislation appears to favour the Protestant phrasing, despite the presence of a Catholic minority comprising about 22% of the state’s population.

“Even among those who may believe in some version of the Ten Commandments, the particular text that they adhere to can differ by religious denomination or tradition,” the allied groups said in their statement. “The government should not be taking sides in this theological debate, and it certainly should not be coercing students to submit day in and day out to unavoidable promotions of religious doctrine.”

Similar bills have been proposed in three other states – Texas, Oklahoma and Utah – but, amid threats by opponents to mount legal challenges, they have yet to become law.

A similar law passed by Kentucky in 1980 was struck down by the US supreme court on the grounds that it violated the establishment clause in the constitution’s first amendment, which says Congress can “make no law respecting an establishment of religion”. The court ruled that the Kentucky law served a plainly religious purpose.

However, some analysts suggest that Louisiana Republicans – a southern state within the US’s traditional “Bible belt” where the party enjoys a two-thirds supermajority in the state legislature – have been emboldened by the current rightwing makeup of the supreme court, where there is a six-to-three majority of conservative justices.