In our discussions with advocates of redefining marriage, we often hear that defenders of marriage and sexual difference are overreacting to cultural and legal changes. “You run around yelling that the sky is falling,” we’re told. “We’ve had same-sex marriage for a decade now in Massachusetts, and guess what: The sky is not falling.”

This is not an argument, of course, but an attempt to end any discussion of what it would mean to remove sexual distinctions from the law. As it did to James Bond’s psychiatric evaluation in the recent hit movie, the mention of the phrase “sky fall” is supposed to terminate the proceedings.

No serious participants in the current marriage discussion are running around like Chicken Little. Defenders of marriage are concerned primarily about the long-term implications of redefining the institution. We might not expect the redefinition of marriage to alter cultural practices dramatically right away. After all, it took nearly two generations to realize the full effects of the divorce revolution of the 1960s and 1970s. But strange things are nevertheless happening in Massachusetts, where sexual difference was eliminated from marriage laws in 2003.

Two years ago, the Massachusetts legislature enacted a statute prohibiting, among other things, discrimination in public schools on the basis of “gender identity.” The law defines gender identity as “a person’s gender-related identity, appearance or behavior,” which is not determined by “the person’s physiology or assigned sex at birth.”

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On the basis of that statute, the Massachusetts Department of Education (MDOE) has now eradicated sexual distinctions from public schools. MDOE’s new directive requires schools to let children use bathrooms and play on sports teams according to the gender they personally identify as theirs, not their anatomical sex. The directive also admonishes schools to eliminate sex and gender distinctions in graduation garb, physical education, and other practices.

Under Massachusetts law, the connection between gender identity and sexual distinction is now considered a historical accident, the result of arbitrary (at best) or mistaken documentation at birth. MDOE’s directive explains:

One’s gender identity is an innate, largely inflexible characteristic of each individual’s personality that is generally established by age four, although the age at which individuals come to understand and express their gender identity may vary based on each person’s social and familial social development. As a result, the person best situated to determine a student’s gender identity is that student himself or herself.

Because the child is solely responsible for identifying his or her own gender, the regulations require school officials to seek the student’s permission before disclosing the student’s gender identity to his or her parents.

That’s not all. The regulations suggest that students who don’t endorse a fellow student’s gender identity may be subject to punishment. After condemning bullying, the directive endorses a memorandum that a Massachusetts school principal sent to teachers instructing them to discipline students who intentionally refer to a transgender student by his or her given name, or the pronoun corresponding to his or her anatomical sex. Such behavior “should not be tolerated.”

MDOE justifies these regulations on pedagogical grounds: “All students need a safe and supportive school environment to progress academically and developmentally.” By “all students” MDOE must mean all students who share MDOE’s conception of sex and gender as an individual choice.

It is not difficult to imagine who will embrace MDOE’s conception. The regulations state, “A student who says she is a girl and wishes to be regarded that way throughout the school day and throughout every, or almost every, other area of her life, should be respected and treated like a girl” (emphasis ours). The caveat that the student might want to be treated like a boy for some purposes seems an implicit admission that gender identity is not, in fact, an inflexible characteristic, as MDOE insists, but rather can adjust over time. And the directive states that the law “does not require consistent and uniform assertion of gender identity” (emphasis original).

While we doubt that teenage boys will take much interest in the provenance of gender personality, it’s not a stretch to suppose that they will welcome its implications for co-ed activity.

Perhaps this is why many parents in Massachusetts find these regulations shocking. We must confess that we are not so surprised. Massachusetts lawmakers have for many years been eradicating sexual distinctions from the law. This result seems to us the logical consequence of those efforts.

Redefining marriage to eliminate sexual complementarity as an essential characteristic doesn’t automatically commit a state to forcing girls to share locker rooms with boys. But there is a logical connection. One of the premises justifying the redefinition of marriage also grounds these new regulations, that is, the view that sexual difference is irrelevant to the practice of marriage.

But if sexual difference is irrelevant to marriage, then how can it be relevant to any practices? Once the state has determined that sexual difference is no longer a legitimate reason to extend special recognition to man-woman monogamy, there is no reason in principle to maintain sexual distinctions in less intimate practices. If one’s anatomical reality isn’t relevant to one’s marriage, it’s even less obvious why it should be relevant to one’s bathroom choice.

To be sure, there are prudential implications of eradicating sexual distinction from education laws. But if letting people identify their own gender is a matter of justice, then it’s the job of law to solve the practical problems of implementation. (That is a key lesson of civil rights legislation.)

Though future practical problems might seem obvious, the law makes it far from clear that there are any. If a boy who identifies as a girl really is a girl, as the law declaims, then any perceived harms resulting from his presence in a girls’ locker room are illusory. No wonder the Commonwealth exhorts school officials to discipline students who object to the arrangement.

There are other indications that those who perceive inherent differences between men and women will increasingly be marginalized from public life in Massachusetts. A few months ago, a federal court in Massachusetts ruled that the United States Constitution requires the Commonwealth’s Department of Corrections to pay for a sex-change surgery requested by an inmate who is serving time for murder. It is cruel and unusual punishment, the court reasoned, to force the prisoner to keep his anatomy intact while he is incarcerated.

This ruling might seem unrelated to removing sexual distinctions from law, but for the court’s reasoning. The court discredited the Commonwealth’s expert witnesses, who expressed doubt that a sex-change surgery is medically necessary, and who recommended treating the prisoner’s psychological and emotional disorders instead.

The court ruled that these recommendations are “not within the range that would be acceptable by prudent professionals.” In other words, the court decided that no prudent professional would deny sex-change surgery to a male prisoner who identifies himself as a woman.

The lesson is clear. If you think male and female are two distinct sexes determined by your anatomy at birth, then don’t bother serving as an expert witness in the United States District Court in Massachusetts. Nor can you in good conscience send your children to public school in the Commonwealth. A view of human nature that until very recently was understood to be obvious is becoming a source of disqualification from participating in public life.

As lawyers, we perceive the logic of this latest regulatory innovation. But as fathers, we think that those who are dismayed by MDOE’s regulations are the only Massachusetts residents who can plausibly claim to be in their right minds. If the sky is not falling then it is at least showing ominous fissures.