OVER HALF a century ago, Congress struck a blow for gender equality when it passed the Civil Rights Act of 1964. Title VII of that law, which made it illegal for employers to discriminate “because of sex”, has been interpreted to uphold the rights of women to be hired for a so-called “man’s job”; to get promotions without having to wear make-up or behave “more femininely”; to work in offices where sexual favours are not an implicit job requirement; and not to be passed over for a position because they have young children. The courts have read the law to protect men, too. Sexual harassment of male employees counts as sex-based discrimination even if Congress was not contemplating that particular scourge when drafting the law.

Two more facets of workplace mistreatment, and flashpoints in the culture wars, will come before the Supreme Court in a pair of oral arguments on October 8th. Does Title VII’s prohibition on sex discrimination protect gay and lesbian people from being fired on the basis of their sexual orientation? Does it safeguard transgender workers from similar bias? The briefs for the plaintiffs in Altitude Express, Inc. v Zarda, Bostock v Clayton County, Georgia and R.G. & G.R. Harris Funeral Homes Inc. v Equal Employment Opportunity Commission are in—and they are persuasive.

The individuals at the centre of the cases are Gerald Bostock, a social worker in Georgia who was sacked after joining a gay softball league; Donald Zarda, a sky-diving instructor in New York whose sexual orientation also cost him his job (he has since died); and Aimee Stephens, an embalmer whose presentation as a transgender woman led to her dismissal from her position at a funeral home in Michigan. Mr Zarda and Ms Stephens won their cases in the Second and Sixth Circuit Courts of Appeals, respectively, while Mr Bostock lost his bid at the Eleventh Circuit.

The loss in Bostock was not a particular surprise, as the Eleventh Circuit has shifted to the right with three recent judicial appointments by President Donald Trump. But the analysis in the published opinion was remarkable for its dismissiveness. Mr Bostock’s discrimination complaint, the court ruled, was invalid under a circuit-court decision from 1979. Yet that case, Blum v Gulf Oil Corp., arrived nearly a decade before Price Waterhouse v Hopkins, a 6-3 Supreme Court decision siding with a female employee who had been denied a promotion for failing to adhere to stereotypically feminine norms of appearance and behaviour. When the Eleventh Circuit voted 9-2 against reconsidering Mr Bostock's complaint “en banc” (as a full court), the dissenters were incredulous. They could not grasp “why a majority of our court is content to rely on the precedential equivalent of an Edsel with a missing engine" with the rights of “so many people” at stake.

Expanding gay rights via an old statute might seem like a stretch for a Supreme Court with a five-justice conservative majority that now lacks Justice Anthony Kennedy, who authored four landmark opinions vindicating the rights of gay and lesbian people. It may be. But the most promising arguments running through four dozen briefs from the plaintiffs and their supporters do not try to push the justices toward any particularly radical ideas. No newfangled rendering of Title VII is necessary to find for the LGBT plaintiffs, the briefs say. Even if the courts stick to the conception of “sex” as anchored by biology and genetics (with no gestures toward social roles or queer theory), the gay and trans workers should win. And the briefs—including the one filed by Ms Stephens’s lawyers—wisely stick to the conservative justices’ favoured method of interpreting statutes: textualism, which considers how a law is written, rather than how its drafters imagined it would be applied.

In a brief prepared for several former solicitors general, Joshua Matz, a lawyer in New York, and Laurence Tribe, a Harvard law professor, begin by reminding the court that the meaning of a law “is distinct from how people may have expected the statute would apply when it was enacted”. Citing Oncale v Sundowner Offshore Services, Inc.—a 1998 Supreme Court decision recognising that Title VII bars sexual harassment of male employees—the authors recall the late Justice Antonin Scalia’s clarion call to textualism: “it is ultimately our laws rather than the principal concerns of our legislators by which we are governed”.

The brief then turns to the “plain text” of Title VII and observes how it protects LGBT people. It’s not necessarily because “sex” means “sexual orientation” or “gender identity”, the brief argues, but because an employer logically cannot fire someone on one of these bases without paying close attention to their perceived or actual sex, and applying stereotypes governing how people of that sex should present themselves or whom they should be attracted to. When you fire someone for being transgender, the brief reasons, you are saying they should behave and dress in ways that match standards attached to their biological sex. When you fire an employee for being gay, you are saying their sex dictates a particular object of romantic interest. Neither dismissal would have occurred had the employee been born to the opposite biological sex, or absent the stereotypes harboured by the employer. Both firings, Messrs Matz and Tribe conclude, are therefore discrimination “because of sex”.

A similar path to victory for Ms Stephens is outlined in a brief by several law professors. The court need not resolve whether transgender status is itself a protected category under Title VII, the filing reads. It must only take account of the facts of the case and apply Price Waterhouse, which bars employers from drawing upon sex-based stereotypes when making hiring and firing decisions. Ms Stephens was sacked “because she planned to disregard certain workplace norms” that her boss “imposed only upon funeral directors whom he considered to be ‘men’”. This is analytically indistinguishable from a woman being too masculine for a promotion, or a job being too manly for a woman. The brief also addresses the respondents’ contention that a win for the plaintiffs would prevent an “employer from having separate men’s and women’s toilet facilities”. Not so, the scholars respond: separate bathrooms do not impose “severe harms” on employees. Fears of a “purge of sex-segregated restrooms across the nation are therefore decidedly exaggerated”.

If some of the Supreme Court justices opt to conduct a more searching investigation of how “sex” was understood the 1960s, they will find the plaintiffs’ claims have even greater credence. An illuminating brief from a group of historians shows that the public’s understanding of sexual discrimination in the civil-rights era was “sufficiently broad and multidimensional” to include discrimination against LGBT individuals. Battles against sex discrimination were waged, in part, to enable “men and women to depart from conventional norms of masculinity and femininity, then called ‘sex roles’, without suffering detrimental employment consequences”. A brief filed by 206 businesses—including Amazon, Google, Uber and Wells Fargo—says LBGT individuals’ protection from discrimination would boost innovation, diversify the workforce and increase productivity.

Few lawmakers may have had anti-gay and anti-trans discrimination in mind 55 years ago when they passed the Civil Rights Act. But the language they approved is sweeping, and on a court that emphasises a statute’s words—the text itself, not Congress’s purposes or expectations—chances of a new horizon for Title VII seem favourable. If the Supreme Court ends up expanding the Title VII umbrella to protect some 10m Americans from having their gender identity or sexual orientation serve as the basis of discriminatory treatment, the jurisprudential path could be paved not in radical redefinitions of contested concepts but in syllogisms rooted in well-grounded premises.