On Monday, the Supreme Court agreed to decide whether Title VII of the Civil Rights Act of 1964 prohibits employment discrimination against LGBTQ people. The answer to this question should be obvious: Of course Title VII’s bar on discrimination “because of sex” encompasses discrimination on the basis of sexual orientation and gender identity; there is no way to discriminate against LGBTQ people without taking sex into account. But this court’s majority may disagree. There appears a good chance that the conservative justices will warp the law to exclude gender and sexual minorities from federal workplace protections. The result will be an unprecedented rupture in civil rights law that threatens far more than just LGBTQ people.

Dozens of federal courts, including the 2nd and 7th U.S. Circuit Courts of Appeals, have ruled that Title VII’s bar on sex discrimination forbids gay employment discrimination. There are three overarching reasons why. First, it is impossible to discriminate against gay and bisexual people without factoring in their sex: If a man gets fired for dating a man but would not get fired if he were a woman, his sex is a key element in his termination. Second, this discrimination punishes individuals for intimately associating with people of the same sex. Consider an analogy to interracial marriage: When an employer discriminates against a white employee for marrying a black person, he has committed race discrimination. Similarly, when an employer discriminates against a male employee for marrying another man, he has committed sex discrimination.

Third, and perhaps most importantly, LGBTQ discrimination constitutes sex stereotyping—which is illegal under the Supreme Court’s decision in Price Waterhouse v. Hopkins. In that case, the court said that employers may not penalize a woman for failing to conform to gender norms by, say, acting too “masculine” at work. And as the 7th Circuit explained, gay people represent “the ultimate case of failure to conform” to a sex stereotype: By partnering with people of the same sex, gays violate the quintessential gender norm, heterosexuality. So, for instance, a lesbian’s discrimination claim “is no different from the claims brought by women who were rejected for jobs in traditionally male workplaces, such as fire departments, construction, and policing. The employers in those cases were policing the boundaries of what jobs or behaviors they found acceptable for a woman.”

With regard to transgender people, the logic is even simpler. When an employer discriminates against an individual for transitioning from one sex to another, he must take sex into account. Moreover, if an employer punishes a worker for transitioning, he is penalizing her for failing to conform with the sex assigned to her at birth. If Price Waterhouse is to remain good law, then the court must acknowledge that anti-trans discrimination is, at its core, a form of sex stereotyping.

Subtract politics from the calculus here, and the truth of these theories becomes obvious. So obvious, in fact, that a good number of very conservative judges has endorsed them. To take a partial sample: Judge William Pryor, a firebrand reactionary on Donald Trump’s Supreme Court shortlist, agrees that anti-trans discrimination constitutes unlawful sex stereotyping. Judge Dennis Jacobs (a George H.W. Bush appointee) and Judge Peter Hall (a George W. Bush appointee) of the 2nd Circuit believe that anti-gay discrimination is sex discrimination under Title VII. So do Judges Joel Flaum, Kenneth Ripple, and Frank Easterbrook of the 7th Circuit—all Ronald Reagan appointees. These ideas are not wacky ultra-liberal postulations. They are grounded in text and precedent, emanating from the words of the law itself.

There are two basic counterarguments to these theories. The first, endorsed by Trump’s Department of Justice, is that Title VII only bars “sex-based treatment of women as inferior” to men, and vice versa. In other words, an employer only runs afoul of federal law if he fires a woman because he believes women are inferior to men. The second, touted by dissenters on the 2nd and 7th Circuits, is that Congress did not intend to outlaw LGBTQ discrimination when it passed the Civil Rights Act in 1964.

Because this first rejoinder is so utterly divorced from any known theory of Title VII adopted by any court in the past several decades, it should be dismissed out of hand, as the 2nd Circuit did. It is, after all, directly contradictory to Price Waterhouse in its cramped interpretation of sex discrimination. The second rejoinder seems more plausible, which makes it more dangerous—and not just to LGBTQ people. That’s because the Congress that passed Title VII did not really understand the law, and if the Supreme Court uses its intentions as a guidepost, it will upend the entire federal nondiscrimination regime.

As Gillian Thomas explains in her book Because of Sex, Title VII did not originally contain any bar on sex discrimination. The word sex was added by a virulent racist, Rep. Howard Smith of Virginia, who did not want black women to have more protections than white women. There was minimal floor debate on Smith’s addition, which slipped through with little public comment. For nearly a decade, the federal government essentially ignored this provision of the law. An early executive director of the Equal Employment Opportunity Commission, which helps to enforce Title VII, called the bar on sex discrimination “a fluke” that was “conceived out of wedlock.” Another executive director said, “Don’t worry, we aren’t going to make men hire male secretaries.”

In the absence of any evidence of what Congress meant to do in 1964, judges should look at the text of the law.

There is no evidence that when Congress approved Title VII in 1964, it had a clear idea of what conduct it had just proscribed. We can safely assume, however, that a majority of congressmen did not believe they had forbidden sex stereotyping. We can also assume that few congressmen believed they had prohibited sexual harassment. Title VII, after all, contains no explicit bar on sexual harassment; it only outlaws discrimination “because of sex.” As late as 1975, federal judges refused to recognize that sexual harassment could amount to sex discrimination. Indeed, only after legal theorists spent years developing this doctrine did courts begin to understand that, by creating a hostile workplace through sexual advances, an employer could engage in discrimination “because of sex.” And the Supreme Court did not ratify this theory until 1986 in Meritor Savings Bank v. Vinson.

Today’s near-universal acceptance that Title VII bars workplace sexual harassment would probably be shocking to Rep. Howard Smith—just as shocking as the developing consensus that the law bars LGBTQ discrimination. And therein lies the profound danger of the coming Supreme Court cases. If the conservative majority interprets Title VII by speculating how the law was originally understood, it will clear away decades of precedent protecting not just LGBTQ people, but also women, and anyone who does not conform to an employer’s expectations of gender norms. Price Waterhouse will be gone. So will Meritor Savings Bank. So too will thousands of lower courts decisions rooted in the doctrines that courts have developed to interpret the law’s sweeping yet hazy command.

There is another way. In the absence of any evidence of what Congress meant to do in 1964, judges should look at the text of the law. The statute’s text forbids employers from taking sex into account when penalizing a worker. And no employer can punish an employee on the basis of their LGBTQ status without taking their sex into account.

Perhaps Chief Justice John Roberts will join the liberals in embracing this definition. During arguments in Obergefell v. Hodges, Roberts appeared to embrace the reasoning that anti-gay discrimination is sex discrimination, stating: “If Sue loves Joe and Tom loves Joe, Sue can marry him and Tom can’t. And the difference is based upon their different sex. Why isn’t that a straightforward question of sexual discrimination?” Yet Roberts’ eventual dissent in Obergefell evinced a profound hostility to the rights of sexual minorities and made no mention of the sex discrimination analogy.

Which way will Roberts lean now? It is a safe bet that his four arch-conservative colleagues are prepared to vote against LGBTQ rights under the pretense of judicial modesty. There is an outside chance that Roberts will resist the urge to cast a political vote and prioritize the text of Title VII instead. But that outcome seems unlikely. Roberts’ Obergefell dissent indicated that the chief justice is unwilling to interpret the laws and the Constitution to safeguard LGBTQ people, even when, as he seemed to admit during oral arguments, there is a strong case for doing so. If he and the conservative justices sever LGBTQ people from Title VII, they will have favored partisan biases over the text of federal law—and launched on assault on federal civil rights law as we know it, one that puts millions of Americans in jeopardy.