Mississippi Gov. Phil Bryant signed a bill that could lead to student-led prayer over school intercoms or at graduations or sporting events. The law becomes effective July 1.
The American Civil Liberties Union says the law is likely to prompt a lawsuit.
The law says all school districts must adopt a policy to allow a "limited public forum" at school events such as football games or morning announcements, to let students express religious beliefs. The policy must include a disclaimer that such student speech "does not reflect the endorsement, sponsorship, position or expression of the district."
Meanwhile, a nonprofit conservative group says it will provide free legal representation to Mississippi schools or districts if a new school prayer law is challenged in court.
Liberty Counsel attorney Steve Crampton told The Associated Press Friday that the group believes the law is constitutional.
Bear Atwood, legal director for American Civil Liberties Union of Mississippi, says she thinks the law "has serious constitutional issues." She says the ACLU is likely to file a lawsuit to challenge it, if proselytizing takes place in schools.