Let’s begin with a simple question. What’s the purpose of nondiscrimination law? As a general matter, such laws are not designed to eliminate all discrimination on the basis of the protected characteristic. Instead, the desire is to eliminate invidious discrimination. The phrase “invidious discrimination” is critical. It’s a legal term of art that generally means “a classification which is arbitrary, irrational and not reasonably related to a legitimate purpose.”

Indeed, the effort to eliminate all discrimination based on protected characteristics can result in unjust and nonsensical outcomes. Do we want laws holding that separate male and female lockers and showers are per se unlawful? Or should there be no legal preference for female guards to perform strip searches of female prisoners? Should we end the distinction between male and female sports and simply say that the best athlete gets the spot? In each of these circumstances, a truly sex-blind system would actually hurt women—achieving a result the opposite of the law’s intent.

On the other hand, we also know what invidious sex discrimination looks like. We see it in hostile environment sexual harassment, when women are subjected to gross, sexist abuse in the workplace. We see it when employers refuse to hire female workers because they “might get pregnant.” We see it in quid pro quo sexual harassment, when women are coerced into trading sex for promotions or pay raises. In those circumstances, nondiscrimination law stands as a firewall against systemic injustice and exploitation.

A truly effective and just nondiscrimination law does its best to navigate the distinction between invidious and benign (or even necessary) acts of discrimination. It recognizes the limits of the state’s interests, and it pulls back when it conflicts with fundamental constitutional rights.