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The Supreme Court will hear oral argument Tuesday on whether federal law protects gay people from job discrimination. The judges’ questions will focus on an abstract legal theory called textualism. That will determine whether the Court’s conservative majority overcomes its political hostility to gay rights and enforces the plain language of the law.

The issue in Bostock v. Clayton County is whether Title VII of the Civil Rights Act of 1964, which prohibits sex discrimination in employment, covers discrimination on the basis of sexual orientation and gender identity. The argument for protection is simple. An employee who dates women is “homosexual” only if that employee is female. Treating a woman worse because she is a woman is sex discrimination.

A common rejoinder is that Congress did not intend to protect gay people. But the conservatives who are a majority of the Court have embraced a theory of interpretation called textualism, which holds that laws should be interpreted only on the basis of a statute’s plain language, not what the authors thought but did not say. Textualism has been a convenient theory for conservatives because they can ignore what Congress intended and creatively construe laws to mean what they want them to mean. Thus, for instance, the 1925 Federal Arbitration Act, originally intended to encourage arbitration of commercial disputes, has been used to deny employees the right to sue for wage theft or violence on the job.

Sometimes, however, the text is clear and there is no wiggle room. The court has in the past construed sex discrimination broadly, to include sexual harassment and hostile work environments, even though neither was discussed by Congress in 1964. If someone is mistreated in these ways because of their sex, that is sex discrimination. As the late Justice Antonin Scalia, the leader of the textualist movement, explained when he held that same-sex sexual harassment was covered by the law, “it is ultimately the provisions of our laws rather than the principal concerns of our legislators by which we are governed.”

That means that, even if the legislators would have been surprised to learn that they were protecting gay employees, that doesn’t matter. The words of the law prohibit sex discrimination.

Those who oppose this argument, including the Trump administration, have tried various strategies to evade this result: They rely for example on distinctions between “sex” and “homosexuality” that feel familiar but which do not appear in the statute, or the general expectations that were part of the law’s cultural background. All are at war with the imperative to follow the text.

None of the Court’s five conservatives has ever voted to support a gay rights claim. Here their conservatism is in deep tension with their textualism. The plain language of the law points to a result that they’re not politically inclined to like. So this case is a good test of whether textualism can keep judges from following their own political preferences, as Scalia always claimed it would.

Look for signs that the judges are thinking about the political context. That’s not necessarily a bad thing for the people who are claiming discrimination. This case provides the Court with an opportunity to prove the cynics wrong, and to show that it really does take textualism seriously. Enforcing the statute as written would create a dramatic victory for the gay rights side, but the stakes are lower than in many Supreme Court cases. It would only accelerate the inevitable. A federal statute protecting gay people from employment discrimination is coming. The Equality Act recently passed the House of Representatives. That is as far as it will get this year, because the Republicans control the Senate and the presidency. But political fortunes shift and that won’t always be the case. It has already attracted Republican votes. Protection of LGBT people from employment discrimination, which is what Title VII offers, is supported by 92 percent of Americans.

Chief Justice John Roberts clearly is concerned about the Court appearing to be a partisan tool. He is so worried about the notion of Democratic judges and Republican judges that he was willing to get into a public argument with President Trump about it. An honest textualist reading of Title VII helps the Court with that problem. It confounds narratives on right and left about the partisanship of the Court. It would bolster confidence in the institution, and thus, in a small way, lower the level of polarization and distrust that is destroying American politics.

Andrew Koppelman, John Paul Stevens Professor of Law at Northwestern University, is the author of Burning Down the House: How Libertarian Philosophy Was Corrupted by Delusion and Greed (St. Martin’s Press). Follow him on Twitter @AndrewKoppelman.