ATLANTA — In a setback for gay rights advocates hoping for an expansion of workplace discrimination protections, a federal appeals court in Atlanta has ruled that employers aren’t prohibited from discriminating against employees because of sexual orientation.

A three-judge panel of the 11th U.S. Circuit Court of Appeals on Friday ruled 2-1 that Title VII of the Civil Rights Act of 1964, which prohibits workplace discrimination based on a variety of factors, doesn’t protect against workplace discrimination based on sexual orientation.

The case was one of two that Lambda Legal had pending before federal appeals courts — along with an Indiana case at the 7th U.S. Circuit Court of Appeals in Chicago — that the LGBT rights group had hoped would mark a significant step forward for gay rights.

Jameka Evans in April 2015 sued her former employer, Georgia Regional Hospital in Savannah, alleging that she was discriminated against and effectively forced from her job as a security guard because she is a lesbian and didn’t conform to gender norms.

Visiting Judge Jose E. Martinez wrote in the majority opinion that the court was bound by precedent set by a 1979 case that said Title VII doesn’t prohibit "discharge for homosexuality." Other circuits have also found that sexual orientation is not a protected class under that law, Martinez wrote.

An 11th Circuit decision from 2011 said discrimination against a transgender employee because of gender non-conformity amounted to sex discrimination and was not allowed, and Evans’ attorneys argued it should also protect gays and lesbians who claimed discrimination based on their sexual orientation.

Circuit Judge William Pryor, who was a party to that opinion, argued in a concurring opinion that the transgender case, which involved a legislative aide who was fired after telling her boss she planned to undergo a gender transition, was based on behavior rather than status.

"A gay individual may establish with enough factual evidence that she experienced sex discrimination because her behavior deviated from a gender stereotype held by an employer, but our review of that claim would rest on behavior alone," Pryor wrote.

Pryor also argued that it was up to Congress, not the courts, to declare sexual orientation a protected class.

Circuit Judge Robin Rosenbaum wrote in a dissenting opinion that it is time for the court to recognize that the law prohibits workplace discrimination based on an employee’s sexual orientation because that is discrimination based on sex.

"Plain and simple, when a woman alleges, as Evans has, that she has been discriminated against because she is a lesbian, she necessarily alleges that she has been discriminated against because she failed to conform to the employer’s image of what women should be — specifically, that women should be sexually attracted to men only," Rosenbaum wrote.

Evans’ lawsuit also included a claim that she was targeted because of gender-based behavior, notably dressing like a man and having a male haircut. The majority opinion said that could amount to a claim that’s not based on her sexual orientation and instructed the lower court to allow her to amend her initial lawsuit to try to bolster that claim.

In a similar case, a three-judge panel of the 7th U.S. Circuit Court of Appeals in Chicago in July upheld a lower court’s dismissal of a 2014 lawsuit filed by Kimberly Hively of South Bend, Indiana, a former part-time instructor who said Ivy Tech Community College in her hometown didn’t hire her full time because she is a lesbian.

The full 7th Circuit vacated that panel’s decision, and all 11 of the court’s judges reheard the case in November. The ruling has not yet been announced, but several of the judges seemed to signal during oral arguments that they were ready to broaden the scope of the 53-year-old civil rights law.

Lambda Legal attorneys said they plan to ask the 11th Circuit to vacate the Evans ruling and have the full 11-judge court rehear the case, like the 7th Circuit did in the Hively case.

"This is not the end of the road for us and certainly not for Jameka," attorney Greg Nevins said in an emailed statement. "There is no way to draw a line between sexual orientation discrimination and discrimination based on gender nonconformity because not being straight is gender-nonconforming, period."