Introduction
In the last few years, the concept of “sex assigned at birth” has appeared with increasing frequency in U.S. case law on discrimination against transgender people.
The phrase had been used, at least since the 1960s, to describe an obstetrician’s “casual pronouncement of the newborn as a male or female,” “based upon inspection of the external genitalia.”
This pronouncement, then and now, results in a male or female designation on a child’s birth certificate that is sometimes considered the person’s legal sex, unless changed through formal processes.
Over the past two decades, the concept of sex assigned at birth has been taken up by transgender rights advocates to replace the troublesome term “biological sex.”
Assigned sex is opposed to gender identity—an individual’s own internal sense of whether they are a man, a woman, or nonbinary.
It is the basis for the legal definition of “transgender”: having a gender identity that does not match the one expected for an individual’s sex assigned at birth.
It appeared in 2016 regulations interpreting the Affordable Care Act
and in a proposed 2021 federal law that would bar discrimination on the basis of LGBTQ status in employment, health care, and housing.
But courts have been reluctant to embrace the concept. In the Supreme Court’s landmark Bostock v. Clayton County decision, which held that Title VII of the Civil Rights Act forbids discrimination against transgender people, the Court declined to use the term sex assigned at birth.
Instead, it proceeded on the assumption that “sex” refers “only to biological distinctions between male and female.”
In this respect, Bostock is representative. Many federal court decisions fail to critically consider the differences between sex assigned at birth and “biological sex” or even conflate the two concepts.
This confusion is dangerous. In the wake of Bostock, there has been an unprecedented onslaught of federal and state legislation aimed at curtailing transgender rights,
almost all of it directly invoking the idea of “biological sex.”
Federal courts will soon be asked to consider the definition of sex as they resolve challenges to new laws in eighteen states barring transgender women and girls from sports,
two laws banning certain forms of gender-affirming health care for transgender youth,
three laws limiting restroom access,
and three laws restricting a person’s ability to change the sex designation on their identification documents.
Although a “growing consensus” of courts agree that it is impermissible discrimination for schools to refuse to allow transgender students to use restrooms consistent with their gender identities,
the Eleventh Circuit is currently reconsidering the issue en banc.
Bostock declined to spell out its implications for restrooms, sports, identity documents, or other such controversies, and so transgender rights may end up back in the Supreme Court again soon.
This Article attempts to uncover the history of the concept of sex assigned at birth, as well as that of its main competitor, “biological sex,” and to set forth the case in favor of the shift toward sex assigned at birth as an idea that can advance legal protection for transgender, nonbinary,
and gender-nonconforming people.
One contribution of this Article is to excavate the histories of the concepts of “biological sex” and “sex assigned at birth.”
In recent years, many courts and legislatures have taken for granted that there is some simple attribute called “biological sex” that is easily separable from gender identity.
In litigation over access to sex-segregated restrooms and sports, opponents of transgender rights lean heavily on “biology” as a simple and scientific basis for excluding transgender individuals from the categories of “male” and “female.”
But the idea of “biological sex” as distinct from gender identity is not a time-honored scientific or legal category; it is a contested concept from mid-twentieth-century medicine. In the 1970s, “biological sex” found its way into legal doctrine as a result of an outdated understanding of transgender identity as a mental illness caused by early childhood experiences, along with policy concerns about the need to distinguish the sexes for purposes such as avoiding same-sex marriage.
Lawmakers today are unable to agree on any definition of “biological sex” based in anatomy, genetics, hormones, or other such properties, so they often enact laws that define sex as the male or female designation on an individual’s original birth certificate.
Rather than vindicating any biological standard, these laws endeavor to exclude transgender people. Assigned sex terminology also emerged at midcentury in medical research related to people with intersex variations. “Intersex” is “an umbrella term for differences in sex traits or reproductive anatomy,” such as “differences in genitalia, hormones, internal anatomy, or chromosomes, compared to the usual two ways that human bodies develop.”
Transgender theorists borrowed this terminology in the 1990s to describe the process of assigning sexes to all infants, and it began to appear in legal contexts in the early 2000s.
It now competes with the term “biological sex” in legal disputes over transgender rights.
Another contribution of this Article is to present the full theoretical case in favor of “sex assigned at birth” as an alternative to “biological sex.”
“Sex assigned at birth” is not a euphemism for “biological sex” but a critique of the very concept. It acknowledges that “sex” can be defined in many ways. To speak of assigned sex is to point out that while administrative “M” and “F” classifications might be simple, the biology of sex is not. “Biological sex” is not binary, stable, or uniform.
And it is inconsistent with medical research to assert that gender identity has no biological underpinnings.
The claim that sex is assigned at birth, rather than being a self-evident biological property that naturally corresponds with certain gender identities and roles, goes beyond the feminist argument against biology as destiny.
Administrative assignments of identities and social roles threaten liberal principles of autonomy that insist that every person should be, at least in part, the author of their own life story,
as well as postmodern sensibilities about the role of creativity and play in constructing the self.
The idea of assignments at birth evokes the egalitarian’s umbrage at lotteries of birth in which roles and opportunities are distributed in infancy.
That these assignments subject individuals to intersecting social hierarchies—such as those that elevate men over women, gender conformers over nonconformers, and cisgender over transgender people—offends theories of the purpose of antidiscrimination law as undermining systemic patterns of subordination.
Moreover, by pointing out that sex is assigned at birth, advocates draw attention to the fact that institutions that exclude transgender people are doing so based on what is essentially a medical record of a doctor’s examination of a person’s genitalia in infancy. Yet genitalia and medical records are quintessentially private.
Thus, the idea that sex is assigned at birth has the potential to disrupt legal invocations of “biological sex” as a simple, natural, neutral, and normatively unproblematic basis for classifying individuals. In practice, however, sex assigned at birth has not lived up to its theoretical potential. Another contribution of this Article is to explain why.
Of course, some oppose the concept due to ideological opposition to transgender rights in general. But the idea has encountered resistance even from those without fixed positions in this particular culture war. One reason is that the idea of “biological sex” as a self-evident essence is an entrenched form of common sense that is difficult to dislodge, even though it has been undermined by advances in science and medicine. The concept is reinforced by the insistence of many feminists that there is an important difference between biological sex and social gender.
Another reason for the persistence of biological sex is dissatisfaction with gender identity as an alternative basis for sex or gender classification. Judges and other decisionmakers are often concerned that gender identity is too subjective and easily manipulated to serve as the basis for sorting individuals into male and female categories.
A final contribution of this Article is to discuss ways to overcome these barriers.
Sex assigned at birth clarifies what is at stake in disputes over restrooms, sports, and identity documents—these are not debates over biology; rather, they are controversies over how to prioritize conflicting values and whether, as an empirical matter, more inclusive policies will have deleterious effects. While sex assigned at birth can clarify what the stakes are, it cannot, on its own, resolve the moral and practical questions at the heart of contemporary transgender rights controversies. This Article cautions against an approach taken by many courts, which is to attempt to evade moral and practical questions by insisting that an individual’s true sex is their gender identity as a man or a woman, if medical experts verify that they live all aspects of their lives consistently with that gender identity. The result of such an approach may be to limit legal protection to only that subset of the transgender community that can prove the bona fides of their gender identities to medical experts and to base the case for protection on a scientific foundation that may not be able to bear its weight. Moreover, this approach is not necessary. A review of recent litigation demonstrates that advocates have won transgender rights cases not just with appeals to scientific authorities on the validity of transgender people’s gender identities but also with arguments that tap into values like equality, autonomy, and dignity, with stories that cultivate empathy, and with evidence debunking practical objections to transgender inclusion.
While theorists and advocates have been deploying the concept of sex assigned at birth for the past two decades,
no work of legal scholarship has explored the idea’s potential for transgender rights arguments, or unearthed the origins of that term and its main competitor, “biological sex.”
Transgender people continue to face uniquely high rates of discrimination, harassment, and violence with devastating consequences.
Moreover, rules requiring that people conform with expectations for their assigned sex impact individuals who do not necessarily identify as transgender but are gender nonconforming or nonbinary.
In addition to its contributions to the study of transgender rights litigation, this Article’s account is of relevance to feminist scholarship on biological concepts of sex and gender.
Part I of this Article uncovers the origins of the debate between “biological sex” and “sex assigned at birth” in transgender rights advocacy and public policy. Part II sets out the theoretical argument for the shift to sex assigned at birth and explains why that concept is superior to alternatives. It demonstrates that sex assigned at birth does useful work in litigation by disrupting the assumption that sex classifications reflect mere biology and pointing to how those classifications can threaten autonomy, equality, privacy, and dignity. Part III explains why courts have been reluctant to abandon biological sex in favor of sex assigned at birth. Part IV offers an analysis of recent transgender rights litigation that concludes that, to overcome this reluctance, the claim that sex is assigned at birth must be accompanied by arguments that speak to values, practicalities, and empathy in particular cases.