Louisiana has become the first state to mandate that the Ten Commandments be displayed in every public school classroom, the latest move by the Republican-dominated Legislature to advance a conservative agenda under a new governor.

The bill, which Republican Gov. Jeff Landry signed into law on Wednesday, mandates poster-sized displays of the Ten Commandments in a “large, easy-to-read font” in all public classrooms, from kindergarten to state-funded universities.

Opponents questioned the law’s constitutionality and vowed to challenge it in court. Supporters said the measure is not just religious but also has historical significance. In the language of the law, the Ten Commandments are “the foundational documents of our state and national government.”

The posters, which will be paired with a four-paragraph “context statement” explaining how the Ten Commandments were “a staple of American public education for nearly three centuries,” must be put up in classrooms by early 2025.

Under the law, no state funds will be used to enforce the order. The cost of the posters will be covered by donations.

The law also “authorizes” but does not require the display of other items in K-12 public schools, including: the Mayflower Compact, signed in 1620 by religious pilgrims aboard the Mayflower and often called America’s “first constitution”; the Declaration of Independence; and the Northwest Ordinance, which established a government in the Northwest Territory — in the present-day Midwest — and created a path for admitting new states into the Union.

Shortly after the governor signed the bill into law at Our Lady of Fatima Catholic School in Lafayette on Wednesday, civil rights groups and organizations that want to keep religion out of government vowed to file a lawsuit challenging it.

The American Civil Liberties Union, Americans United for Separation of Church and State, and the Freedom From Religion Foundation said in a joint statement Wednesday afternoon that the law prevents students from receiving an equal education and prevents children with different beliefs from feeling safe in school.

The groups said, “Even among people who believe in some version of the Ten Commandments, the particular text they follow may vary depending on the religious denomination or tradition. The government should not take sides in this religious debate.”

The controversial law in this Bible Belt state comes during a new era of conservative leadership in Louisiana, after Landry replaced two-term Democratic Gov. John Bel Edwards in January. The GOP has a majority in the Legislature, and Republicans hold every elected position statewide, clearing the way for lawmakers to pursue a conservative agenda.

Similar bills to require the display of the Ten Commandments in classrooms have been proposed in other states, including Texas, Oklahoma, and Utah. However, with threats of legal battles over the constitutionality of such measures, no state other than Louisiana has succeeded in passing the bill into law.

Legal battles over the display of the Ten Commandments in classrooms are nothing new.

In 1980, the U.S. Supreme Court ruled that a similar law in Kentucky was unconstitutional and violated the U.S. Constitution’s Establishment Clause, which states Congress “may make no law respecting an establishment of religion.” The high court found that the law had no secular purpose but instead served a clearly religious purpose.