The Supreme Court will not yet step in to rule on whether federal laws against discrimination on the basis of sex also forbid discrimination on the basis of sexual orientation.
Today the top court declined to hear a lawsuit from a woman in Georgia who claims she was harassed and forced out of her job as a hospital security guard because of her sexual orientation. Lambda Legal, the LGBT-issue-focused legal group that represented her, argues that this violated Title VII of the federal Civil Rights Act of 1964.
That law does not explicitly mention sexual orientation as a protected category, and for much of its history it was treated as though orientation were not included. Many states have chosen over time to add sexual orientation and sometimes gender identity to their own discrimination laws. But Georgia has not.
There is, however, a Supreme Court precedent—established in 1989's Price Waterhouse v. Hopkins—that discrimination based on whether a person expresses stereotypical masculine or feminine behaviors counts as sex-based discrimination. In this security guard's case and similar cases, lawyers argue that discrimination over sexual orientation is rooted in sex-based stereotypes about how males and females should look and behave, and that Title VII therefore covers it after all.
This view of the law does have some federal court rulings supporting it, but it has not made it up to the Supreme Court for a final decision. The interpretation played a significant role in the Obama administration's decision to tell schools they must accommodate transgender students' restroom and locker room choices. The issue of transgender accommodation in schools was heading to the Supreme Court, but when Attorney General Jeff Sessions took over, the Department of Justice reversed its stance, taking the position that federal discrimination laws do not cover sexual orientation or gender identity. Tthe Supreme Court subsequently punted the bathroom case back down to the lower courts, leaving the matter somewhat unsettled as a matter of law.
An 11th Circuit Court of Appeals panel rejected the Georgia woman's claim in March. In April, the 7th Circuit Court of Appeals, which covers Indiana, Illinois, and Wisconsin, determined the opposite—that the Civil Rights Act does prohibit discrimination against gays and lesbians. So there is a split in federal court rulings, making the Supreme Court's decision not to hear the case a bit of a surprise.
The Supreme Court did not indicate why justices are declining to take the case. A representative from Lambda Legal said in a statement that they're going to keep pushing to get the issue in front of the Supreme Court. Unless Congress passes a law settling the matter one way or the other, this seems likely to end up before the Supreme Court eventually.