[Government-imposed] classifications based on sex are subject to intermediate scrutiny. Under intermediate scrutiny, the State must demonstrate that the challenged law serves “‘important governmental objectives and that the discriminatory means employed’ are ‘substantially related to the achievement of those objectives.'” … “[T]he burden of justification is demanding and it rests entirely on the State.” In addition, the justification must be “genuine, not hypothesized or invented post hoc in response to litigation.” Finally, the justification “must not rely on overbroad generalizations about the different talents, capacities, or preferences of males and females.”

[The North Carolina law] classifies citizens on the basis of “biological sex” and requires that each sex use separate multiple occupancy bathrooms, showers, and other similar facilities. Because [the law] facially classifies and discriminates among citizens on the basis of sex, intermediate scrutiny applies.

There is no question that the protection of bodily privacy is an important government interest and that the State may promote this interest by excluding members of the opposite sex from places in which individuals are likely to engage in intimate bodily functions. See, e.g., Faulkner v. Jones, 10 F.3d 226, 232 (4th Cir. 1993) (“The point is illustrated by society’s undisputed approval of separate public rest rooms for men and women based on privacy concerns. The need for privacy justifies separation and the differences between the genders demand a facility for each gender that is different.”); Lee v. Downs, 641 F.2d 1117, 1119 (4th Cir. 1989) (“Most people, however, have a special sense of privacy in their genitals, and involuntary exposure of them in the presence of people of the other sex may be especially demeaning and humiliating.”); see also Doe v. Luzerne Cty., 660 F.3d 169, 176-77 (3d Cir. 2011) (observing that several circuits have recognized “a constitutionally protected privacy interest in [one’s] partially clothed body”); Sepulveda v. Ramirez, 967 F.2d 1413, 1416 (9th Cir. 2012) (stating that “[t]he right to bodily privacy is fundamental” and noting that “common sense” and “decency” protect a parolee’s right not to be observed by an officer of the opposite sex while producing a urine sample); York v. Story, 324 F.2d 450, 455 (9th Cir. 1963) (“The desire to shield one’s unclothed figure from view of strangers, and particularly strangers of the opposite sex, is impelled by elementary self-respect and personal dignity.”). This interest is particularly strong with regard to minors. See, e.g., Beard v. Whitmore Lake Sch. Dist., 402 F.3d 598, 604 (6th Cir. 2005) (“Students of course have a significant privacy interest in their unclothed bodies.”); Doe v. Renfrow, 631 F.2d 91, 92-93 (7th Cir. 1980) (stating that it “does not take a constitutional scholar” to conclude that a strip search invades a student’s privacy rights). At the hearing on this motion, Plaintiffs acknowledged that the practice of segregating bathrooms and other similar facilities on the basis of sex promotes this government interest. (See Doc. 103 at 15-19.)

All parties agree that bodily privacy qualifies as an important State interest and that sex-segregated facilities are substantially related to that interest. But the relevant authorities do not define “sex” or explicitly explain which differences between men and women give rise to the State’s interest in separating the sexes for privacy purposes; generally, these cases simply observe that individuals of one sex have a privacy interest in being separated from “the other sex.”

Not surprisingly, then, the parties disagree about which definition of “sex” promotes the State’s interest in bodily privacy. Defendants contend that bodily privacy interests arise from physiological differences between men and women, and that sex should therefore be defined in terms of physiology for the purposes of bathrooms, showers, and other similar facilities. Plaintiffs, by contrast, implicitly contend that bodily privacy interests arise from differences in gender identity, and that sex should therefore be defined in terms of gender identity for the purposes of these facilities.

To support their position, Plaintiffs submitted expert declarations stating that, from a “medical perspective,” gender identity is the only “appropriate” characteristic for distinguishing between males and females. Defendants have indicated their strong disagreement with this position, though they have not yet offered any evidence on this point in this case. [Footnote: … Defendants recently offered medical evidence in [an accompanying] case.] But regardless of the characteristics that distinguish men and women for “medical” purposes, Supreme Court and Fourth Circuit precedent supports Defendants’ position that physiological characteristics distinguish men and women for the purposes of bodily privacy.

Although the Supreme Court has never had an occasion to explicitly explain which differences between men and women justify the decision to provide sex-segregated facilities, the Court has generally assumed that the sexes are primarily defined by their differing physiologies. In [the Virginia Military Institute case], for example, … [e]ven while rejecting stereotypical assumptions about supposed “inherent differences” between men and women, the Court acknowledged, “Physical differences between men and women … are enduring,” adding that the “two sexes are not fungible.” The Court then linked these physiological differences to privacy considerations, adding, “Admitting women to VMI would undoubtedly require alterations necessary to afford members of each sex privacy from the other sex in living arrangements, and to adjust aspects of the physical training programs.” …

[Indeed], as recently as January 2016, the Fourth Circuit cited [the VMI case] approvingly while concluding that physiological differences justified treating men and women differently in some contexts. See Bauer v. Lynch, 812 F.3d 340, 350 (4th Cir. 2016). In Bauer, a male applicant “flunked out of the FBI Academy after falling a single push-up short of the thirty required of male Trainees.” The applicant sued, noting that his performance would have qualified him under the different physical fitness standards applied to female applicants. The Fourth Circuit found that different standards for men and women arose from the FBI’s efforts to “normalize testing standards between men and women in order to account for their innate physiological differences,” such that an approximately equal number of men and women would pass the tests. In light of this, the Fourth Circuit concluded that the FBI’s policy was permissible because “equally fit men and women demonstrate their fitness differently.” In concluding that the FBI could distinguish between men and women on the basis of physiology, the court explained:

In light of the foregoing, it appears that the privacy interests that justify the State’s provision of sex-segregated bathrooms, showers, and other similar facilities arise from physiological differences between men and women, rather than differences in gender identity. The Fourth Circuit has implicitly stated as much, albeit in dicta, noting:

In fact, even Plaintiffs’ counsel acknowledged the State’s interest in, for example, ensuring that “12-year-old girls who are not familiar with male anatomy” are not exposed to male genitalia by “somebody older who’s showing that to them, a mature adult.” As a result, it appears that the constitutionality of [the North Carolina law] depends on whether the law’s use of birth certificates as a proxy for sex is substantially related to the State’s privacy interest in separating individuals with different physiologies.

There is little doubt that [the law] is substantially related to the State’s interest in segregating bathrooms, showers, and other similar facilities on the basis of physiology. By Plaintiffs’ own allegations, “The gender marker on a birth certificate is designated at the time of birth generally based upon the appearance of external genitalia.”

Plaintiffs contend that birth certificates are an “inaccurate proxy for an individual’s anatomy” because some transgender individuals have birth certificates that do not reflect their external physiology, either because (1) they were born in a State that permits them to change the sex on their birth certificates without undergoing sex reassignment surgery, or (2) they were born in a State that does not permit them to change the sex on their birth certificates, regardless of whether they undergo sex reassignment surgery. But even if the court assumes (contrary to the evidence in the record) that no transgender person possesses a birth certificate that accurately reflects his or her external physiology, Part I would still be substantially related to the State’s interest because, by Plaintiffs’ own estimate, only 0.3% of the national population is transgender. For the remaining 99.7% of the population, there is no evidence that the sex listed on an individual’s birth certificate reflects anything other than that person’s external genitalia. Without reducing the “reasonable fit” requirement to a numerical comparison, it seems unlikely that a law that classifies individuals with 99.7% accuracy is insufficient to survive intermediate scrutiny….

In sum, Supreme Court and Fourth Circuit precedent support the conclusion that physiological differences between men and women give rise to the privacy interests that justify segregating bathrooms, showers, and other similar facilities on the basis of sex…. At this preliminary stage, and in light of existing case law, Plaintiffs have not made a clear showing that they are likely to succeed on their Equal Protection claim.