By Daniel Wiessner

(Reuters) -A federal judge in Texas has ordered three senior lawyers at Southwest Airlines Co to attend "religious liberty training" conducted by a prominent conservative Christian legal rights group, saying they undermined an earlier ruling in a flight attendant's religious bias case.

U.S. District Judge Brantley Starr on Monday said that instead of notifying employees of their rights against religious discrimination, as he had ordered Southwest to do, the lawyers penned a memo warning workers not to violate the company policy that led it to fire the plaintiff, Charlene Carter.

Carter says she was fired for criticizing her union's decision to participate in the 2017 Women's March, a nationwide protest following the inauguration of former President Donald Trump, because Planned Parenthood was a sponsor. Carter has said she is a Christian who opposes abortion.

Starr, a Trump appointee, gave the lawyers until Aug. 28 to attend an eight-hour training conducted by conservative Christian legal group Alliance Defending Freedom (ADF), which is routinely involved in high-profile court cases on abortion and religious liberties.

Judges often require employers to take steps to remedy discriminatory conduct, such as training workers and management, but it is unusual for them to order company officials to undergo training conducted by specific groups. Starr cited older rulings requiring lawyers to attend continuing education or ethics training.

ADF has spearheaded efforts to restrict the availability of abortion pill mifepristone and helped draft a Mississippi abortion ban upheld by the U.S. Supreme Court in its June 2022 ruling eliminating women's constitutional right to abortion.

Monday's ruling may be unprecedented, and the choice of ADF to conduct the training is troubling given its history of advocating a conservative Christian viewpoint, according to David Lopez, who was general counsel of the U.S. Equal Employment Opportunity Commission during the Obama administration.

That could interfere with the lawyers’ constitutional rights, he said, especially if they practice other religions.

“The court is moving into some really dangerous territory here,” said Lopez, who is now a law professor at Rutgers University in New Jersey.

Southwest, Carter's lawyers and ADF, which is not involved in the case, did not respond to requests for comment on Tuesday.

Southwest has maintained that Carter was fired for harassing coworkers about the Women's March on social media in violation of a company "civility policy."

A jury last year found that Southwest and Carter's union had engaged in religious discrimination. Starr ordered them to pay Carter more than $800,000 and reinstate her to her job.

Southwest and the union are appealing that decision, which also required the airline to notify employees of their right to express their religious views on social media.

Starr on Monday said Southwest flouted that order by instead telling employees that "the court ordered us to inform you that Southwest does not discriminate against our employees for their religious practices and beliefs."

Southwest in a memo drafted by the three lawyers - Kerrie Forbes, Kevin Minchey, and Chris Maberry - also defended Carter's firing and said it would continue enforcing its social media policy.

(Reporting by Daniel Wiessner in Albany, New York; Editing by Deepa Babington and Jonathan Oatis)