Last week, the Supreme Court declined to hear a collection of marriage-equality decisions and deferred for another term what seems now an inevitable ruling for marriage equality. The very next day, the Ninth Circuit handed down an opinion, Latta v. Otter, striking down a number of same-sex-marriage bans.

In doing so, the appeals court provided the first of what will surely be many such decisions from which the Court can choose when the justices consider what cases they might hear in the future—and so offers potential rationales by which they might make marriage equality the law of the land. The Ninth Circuit’s majority opinion rejects same-sex-marriage bans because they violate the Equal Protection Clause by discriminating based on sexual orientation, which is a standard reason courts have struck down these bans.

But there is a twist: According to one judge, this is about sexism, too. In her concurrence, Judge Marsha Berzon argues that same-sex-marriage bans also constitute sex discrimination and therefore violate Equal Protection on additional grounds.

In some respects, Berzon’s concurrence was nothing new. Since the beginning of the fight for marriage equality, advocates have argued that a failure to allow same-sex couples to wed amounts to sex discrimination. This argument has, with a couple of notable exceptions, failed in courts. The Hawaii Supreme Court used this logic in 1994 when it issued the first decision in the U.S. for marriage equality (later nullified by a state constitutional amendment), and the argument has only succeeded in a Utah federal district court since then.

The formalist argument is that such bans classify on the basis of sex in a very basic way: In states where a man cannot marry a man, he is deprived of this right by virtue of his sex. That is, were the man a woman, he would have the right to marry his mate.

But Berzon’s opinion pushed past that formalist logic to make a stronger argument that is both nuanced and profoundly true: Laws that discriminate against same-sex couples are, on some level, based in sex stereotypes about what constitutes a “real man” and a “real woman.” The Supreme Court has recognized that laws based on sex stereotypes amount to sex discrimination in violation of Equal Protection. Most famously, in the 1991 case United States v. Virginia, the Court forced the Virginia Military Institute to admit women despite the school’s belief that female candidates were too naturally “cooperative” for its antagonistic methods.

Berzon sees a different shade of sex discrimination in marriage bans. By refusing to recognize the rights of a man who loves a man or a woman who loves a woman, these laws police the boundaries of masculinity and femininity, rejecting identities that challenge traditional gender roles by being “too effeminate” or “too butch.” This reasoning seems intuitively right. Part of homophobia is undeniably sex stereotyping. Long before marriage equality was hip, Adrienne Rich spoke of “compulsory heterosexuality”—part of being a good woman is loving men.

The sex-discrimination argument, if picked up by the Supreme Court, would also have some immediate and sweeping implications for queer people. LGB persons could get a whole host of rights and protections in one fell swoop, without waiting on Congress to pass meaningful legislation.

Take the workplace, for example. The ban on sex discrimination in Title VII of the Civil Rights Act of 1964 has rarely been extended to apply to queer employees (with the exception of Terveer v. Billington, a D.C. District Court decision that reasoned along the same lines as Berzon). The federal Employment Nondiscrimination Act (ENDA) would plug this hole. But efforts to pass the law have stalled, and many organizations that were initially proponents of the legislation have withdrawn their support in the wake of the Hobby Lobby decision, because of the bill’s religious exemptions: Now riddled with loopholes, ENDA would allow discrimination to continue under a façade of religiosity. Were the Supreme Court to adopt this sex-stereotyping argument to effectuate marriage equality, however, it is possible that there would be no need for legislation like ENDA to give voice to arguments about sexual-orientation discrimination in courts, because constitutional and statutory sex-discrimination provisions (including Title VII) could cover sexual-orientation discrimination as well.

This quick fix to sexual-orientation discrimination has some serious appeal, but the fact that sexism and homophobia have much in common is not to say that they are the same. As tempting as the sex-discrimination approach is, it also risks erasing the particular violence of anti-gay bigotry. Homophobia, surely, cannot be understood as sex stereotyping only. Without a recognition of queer people as a protected class, courts’ rejections of same-sex-marriage bans might fail to extend protections to queer people in contexts where the sex/sexuality analogy does not hold. And, worryingly, a legal regime that understands homophobia only as a form of sexism would fail to comprehend the experiences of queer women caught at the crosshairs of two forms of hate.

In some ways, then, Berzon’s argument is a perfect concurrence. She provides a nuanced and persuasive view of the anatomy of bigotry—but this argument should always be secondary, bolstering a central recognition of homophobia on its own terms.

The Supreme Court could ultimately strike down marriage bans on sex-stereotyping grounds. This might, in some ways, be appealing to the justices. In order to decide marriage equality on Equal Protections grounds without a sex-discrimination argument, the Court might have to announce a heightened level of scrutiny for laws that classify on the basis on sexual orientation. This would be a significant expansion of constitutional Equal Protection doctrine, and a sex-discrimination rationale might allow the Court to sidestep such a dramatic ruling.

By contrast, adopting Berzon’s logic alone would prevent the Court from needing to create a new suspect class while acknowledging, at a slant, that marriage bans implicate equality guarantees. But the justices would do more good by paying full respect to the dignity and needs of queer people, rather than by attempting to shoehorn their harms into an older rights schema that doesn’t quite fit.