In the case, Zarda v. Altitude Express, skydiving instructor Donald Zarda sued his employer in 2010, alleging that he was fired because he was gay. The suit claimed that his termination violated Title VII of the Civil Rights Act of 1964, but as BuzzFeed explained last year, the courts' interpretation of Title VII has long been subject to debate.
"Under President Obama, the government argued Title VII's ban on sex discrimination also included gender identity — thereby barring discrimination against transgender workers," BuzzFeed said. "But the Obama administration never went as far to say the civil rights law also covered sexual orientation."
In today's ruling, though, the 2nd Circuit determined that "sexual orientation discrimination is a subset of sex discrimination." Their approach was based on a comparative test: asking whether another trait — in this case, sexual orientation — was being used as a proxy for sex.
"In the context of sexual orientation," wrote Judge Robert Katzmann, who filed the majority opinion, "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. We can therefore conclude that sexual orientation is a function of sex and, by extension, sexual orientation discrimination is a subset of sex discrimination."
The decision is a victory for Zarda's estate (Zarda died in 2014 after a sports accident), but it won't be the last time the issue comes up. The ruling is a rebuke to Attorney General Jeff Sessions: Last year, the Department of Justice filed an amicus brief arguing that Title VII does not prohibit employers from discriminating against gay workers. BuzzFeed notes that various courts have made different rulings on Title VII as recently as December.