What’s unclear is whether that prohibition extends to sexual orientation and gender identity—whether existing federal laws make it illegal for schools to keep transgender kids from using the bathroom that matches their gender identity, for example, or for large businesses to fire people for being gay. These questions have confounded courts since at least 1989, when the Supreme Court ruled in Price Waterhouse v. Hopkins that disparate treatment based on femininity or masculinity—penalizing a woman who refuses to wear skirts or make-up, for example—is illegal. Outside the realm of legal theory, though, it’s difficult to separate a person’s gender performance (how they act out their gender) from their gender identity (whether they identify as male or female) or sexual orientation (who they’re attracted to). In other words: It’s nearly impossible to tease apart the harassment an effeminate gay man might face for his mannerisms, from the harassment he might face over the fact that he has sex with another man when he goes home.

Judges are well aware of this conceptual tangle. Last week, the Seventh Circuit Court of Appeals issued its decision in Hively v. Ivy Tech Community College, a case brought by Kimberly Hively, who claimed she was denied full-time work and promotions because she is a lesbian. She lost, and the reason was straightforward, according to the court: Title VII does not cover discrimination on the basis of sexual orientation. No matter how clear the facts of the case, no matter how explicit the reason for Hively’s stalled out career—it can’t be the basis for a successful suit. Federal law, under which she was suing, does not prohibit employers from refusing to promote lesbians. Because Hively lives in Indiana, she couldn’t sue Ivy Tech under state law, either—the state has no statute that prohibits what she says happened to her.

The Seventh Circuit could have stopped at that, but the judge who authored the decision, Ilana Rovner, went on to include 42 pages of legal research outlining the mess of conflicting decisions that courts have made on this topic. Gender theorists have spent decades trying to disaggregate “sex” from “gender” from “orientation,” but progressive legal groups have done exactly the opposite: They’ve tried to get courts to see all of those concepts as “sex,” with mixed results.

Objections to discrimination based on gender identity have had a bit more success in court than those based on sexual orientation, like Hively’s. When someone goes though a sex-change operation and their colleagues’ behavior toward them changes, for example, “you’re treating someone differently because of their sex than you did when they were the opposite sex,” said Michael C. Harper, a law professor at Boston University. “You’re discriminating against them because they’ve chosen the wrong sex.”