Suppose there are several employees in a particular workplace who regularly engage in some behavior, x. The employer decides to terminate one of these employees, P, citing the fact of P's x-ing. Recognizing that the employer's rationale is insufficient to explain the decision to terminate P while not terminating the other x-ing employees, P challenges the employer to justify this differential adverse treatment.
A logically satisfactory response would require the employer to identify some way in which P, or P's x-ing, is different--i.e., some argument by which P's x-ing provides sufficient reason for P's termination, while not providing comparable reason for terminating the other x-ing employees. Of course, the employer may not be required legally to have any good reason at all for terminating P, so no such response may be necessary, let alone forthcoming. But there is, presumably, at least one important constraint on the reasons to which the employer can lawfully appeal in order to explain why P was singled out for his x-ing: those reasons cannot be discriminatory ones.
But what does this mean? It is tempting to think that it must mean, at least, that the employer cannot lawfully justify P's differentially adverse treatment relative to other x-ing employees simply by appealing to the fact of P's race, color, religion, sex, or national origin. (1) For example, if the behavior in question (x-ing) was arriving late to work, the employer surely could not justify terminating P while not terminating other similarly tardy employees simply by citing the fact that P is, say, of Asian descent. As a matter of law, P's race simply cannot be a consideration that provides reason for treating P's x-ing differently from that of other employees.
But is it really true--for all x and for all P--that the employer in our simple hypothetical case could not lawfully justify the differential adverse treatment of P by appealing to the fact of P's race, color, religion, sex, or national origin? Even without resorting to elaborately concocted counterexamples, we can assign at least one value to x that puts the answer into doubt: Let x be "wearing frilly pink dresses"; (2) let P be a man; and let the other x-ing employees be women. Imagine, now, that the employer responds to P's demand for a justification of his being singled out for his x-ing by declaring, "I am firing you and not them because you are a man, and they are women."
We may or may not be inclined to credit this unvarnished response as adequate from the perspective of a progressive understanding of sex or gender discrimination. Yet, we would surely hesitate to assert--at least as a descriptive claim about the current law--that the employer's explicit appeal to P's sex as the reason for treating him differently establishes ipso facto the fact of intentional discrimination. On the contrary, it is likely that most courts would decline to find actionable sex discrimination here. This implies that there are at least some circumstances in which an employer can legally maintain a policy under which certain behaviors can provide reason to take adverse action against men but not women, and vice versa. In other words, an employer's differentially adverse treatment of one employee as compared to another can sometimes be justified by appeal to the employee's sex, to the effect that--as in our hypothetical--the employer can take adverse action against employees of one sex for engaging in behavior that is deemed acceptable for employees of the other sex.
This implication is at the same time unsurprising and deeply puzzling. It is unsurprising inasmuch as, at some level, one wants to say that of course current employment discrimination law recognizes a legally relevant difference between men and women in the context of regulations governing the way they present themselves in the workplace. Is it not stating the obvious to observe that the law does not require employers to ignore all social norms tied to sex? …