WASHINGTON — The Supreme Court announced Monday that it will decide whether it’s illegal under federal law for employers to discriminate against gay and transgender workers.

The case centers around Title VII of the Civil Rights Act of 1964, which bans discrimination on the basis of race, color, religion, national origin, or sex. The Supreme Court will determine whether “sex” applies to sexual orientation and gender identity as well.

If the Supreme Court rules in favor of the employees claiming discrimination, it will be an important win for LGBT advocates who have been advocating for protections under the Civil Rights Act for decades. It would also be a major hit for the Trump administration, which has openly advocated against the Civil Rights Act applying to LGBT individuals in hearings and briefs.

The court said Monday it will hear three cases on the issue: one from New York, one from Georgia, and one from Michigan. The New York and Georgia cases came to opposite conclusions about whether sexual orientation is protected by the Civil Rights Act. The Michigan case will examine whether gender identity is protected.

The New York case, Zarda v. Altitude Express Inc., was brought by a skydiving instructor claiming he was fired because he was gay. In February, a federal court of appeals for the 2nd Circuit ruled in favor of the employee, concluding that discrimination based on sexuality was a “subset of sex discrimination” because discriminating against someone for being attracted to someone of the same sex was, in part, based on what sex they are.

"A woman who is subject to an adverse employment action because she is attracted to women would have been treated differently if she had been a man who was attracted to women," the majority wrote in the New York appeals court decision. "We can therefore conclude that sexual orientation is a function of sex and, by extension, sexual orientation discrimination is a subset of sex discrimination."

A court in Georgia drew the opposite conclusion, however. A child welfare services coordinator claimed he was terminated for being gay, and the 11th Circuit Court in Atlanta ruled this was legal, citing a 1979 case that ruled the Civil Rights Act did not protect discrimination based on sexuality. Georgia’s ban on consensual sodomy wasn’t overturned until 1998.

When examining the third case, in Michigan, the Supreme Court will consider the separate but related question about whether gender identity is protected under federal law. The case was brought by Aimee Stephens who sued the funeral home where she worked for firing her after she announced she identified as a transgender woman and would start presenting outwardly as female.

The 6th Circuit Court of Appeals ruled in favor of Stephens, concluding that discriminating against an employee because they are transgender was illegal.

The New York and Michigan cases cited Supreme Court precedent that could help their arguments. In 1989 the Supreme Court ruled in Price Waterhouse v. Hopkins that it was illegal to discriminate against workers because they did not conform to ideas of how a certain gender should behave.

Ann Hopkins had claimed she was denied a partnership at Price Waterhouse because she didn’t act feminine enough. The court ruled in that case that Price Waterhouse “had unlawfully discriminated against her on the basis of sex by consciously giving credence and effect to partners' comments about her that resulted from sex stereotyping.”

The Equal Opportunity Employment Commission, a federal agency, cited this precedent as well, in a hearing in the New York case in September, arguing that, “sex stereotyping says that if you are a man attracted to a man, or a woman attracted to a woman, you’re not behaving the way those genders are supposed to behave.”

The Justice Department countered this point in the same hearing, arguing that there is “a common-sense difference between sex discrimination and sexual orientation discrimination.”

The Supreme Court will hear the cases in its next term, which will begin in October 2019.