A growing number of states have passed laws barring discrimination based on sexual orientation. At current count, 22 states have done so. Utah, a state known for its conservative Mormon population, is the most recent addition to that list, having passed a nondiscrimination law in March after a compromise between gay rights advocates and conservative leaders that was heralded as a blueprint for other Republican-led states.

Another blow to sexual orientation bias came this week, when the Equal Employment Opportunity Commission ruled that such discrimination is barred by existing law: Title VII of the Civil Rights Act of 1964.

The commission delivered the decision in the case of a supervisory air traffic control specialist employed by the Federal Aviation Administration in Miami who claimed he was passed over for a permanent position as a front line manager because he is gay. The air traffic control specialist said his supervisor, who was involved in the manager selection process, had made derogatory comments about the complainant’s male partner.

In allowing the complainant’s case to move forward, the five-member EEOC ruled 3-2 that while sexual orientation is not explicitly listed in the Title VII as a prohibited basis for employment decisions, the question is whether an employer relies on sex-based considerations or takes gender into account when hiring, firing, or promoting.

In the air traffic control specialist’s case, the commission said that his claim of sexual orientation discrimination alleges that his employer considered sex when deciding if he should get the permanent job. “The complainant, therefore, has stated a claim of sex discrimination,” the commission said. “Indeed we conclude that sexual orientation is inherently a sex-based consideration, and an allegation of discrimination based on sexual orientation is necessarily an allegation of sex discrimination under Title VII.”

Sexual orientation can’t be defined or understood without reference to sex, and discrimination based on it is “premised on sex-based preferences, assumptions, expectations, stereotypes, or norms,” the ruling says.

The commission acknowledged that federal courts have concluded the opposite—that sexual orientation bias is not covered by Title VII’s ban on sex discrimination—but it said that those decisions are “dated.”

The EEOC’s ruling is a victory for the LGBT community and its supporters, but it does not give a definitive answer to the question of whether employers can discriminate based on workers’ sexual orientation. Courts are not bound to EEOC positions, Marcia McCormick, an employment law professor at St. Louis University School of Law, told Fortune. They are only required to honor legislation and the rulings of courts to which their cases can be appealed, including the Supreme Court. Congress didn’t give the EEOC the power to make regulations with the same force of law as legislation that Congress passes.

But the EEOC’s sexual orientation decision may sway the courts just the same. The commission issued a ruling similar to this week’s in 2012 when it determined that gender identity bias is prohibited by Title VII’s ban on sex discrimination. Most courts that have decided transgender issues lately have agreed with the EEOC’s position or have come to the same conclusion, McCormick says.

Congressional action would put an end to sexual orientation discrimination altogether. The Employment Non-Discrimination Act, which would outlaw discrimination on the basis of sexual orientation (and, in recent versions, gender identity), was first introduced in 1994. Congress has considered it 10 times since then, but it has not become law.