Congress (search) and legislatures can open their sessions with prayers, but a federal judge ruled Friday that school boards do not have the same leeway.

Ruling in a lawsuit brought by a parent against a southeastern Louisiana school system, Judge Ginger Berrigan (search) said school-sponsored prayers in classes or at other school functions have long been prohibited as a violation of First Amendment guarantees against government-established religion.

School boards are integral parts of school systems, she said.

"In officially promoting a religious practice at its governmental meetings, the board is doing what its schools and teachers cannot do, favor religion over nonreligion and endorse particular religious faiths," Berrigan wrote.

School children whose faiths are different from the majority of students are vulnerable to peer pressure and feelings of isolation, Berrigan wrote. "Even without student participation, the board's policy of opening with prayer is an endorsement of religion," the opinion said.

Chris Moody, a lawyer for the school board, said he believes an appeal is likely. An appeal would go to the 5th U.S. Circuit Court of Appeals (search) in New Orleans, which Moody noted has allowed prayer at graduation ceremonies.

The decision was the latest development in a long legal battle over prayer at school functions in Tangipahoa. The lawsuit originally included objections to prayers at Loranger High School football games, but that portion of the lawsuit was settled last year, and prayers were dropped at games and other school events.

The American Civil Liberties Union represented the parent, identified only as John Doe in court documents.

"The court's well reasoned opinion recognizes the ACLU's arguments that parents, children and members of the community should not have to pay the price of religious indoctrination to attend a school board meeting," Joe Cook, executive director of the ACLU of Louisiana, said in a news release.