Leave it to the justice who famously said she could not define what a woman is to weigh in on whether men belong in women’s sports. During oral arguments Tuesday in West Virginia v. B.P.J., Justice Ketanji Brown Jackson again demonstrated how confusion over basic definitions now sits at the heart of one of the most consequential cultural and legal debates before the Supreme Court.
The case centers on whether Title IX and the Equal Protection Clause prevent states from separating boys’ and girls’ sports teams based on biological sex determined at birth. As SCOTUSblog explains, the issue is straightforward in theory: can states preserve sex-based athletic categories, or must they yield to claims rooted in “gender identity”? The answer should hinge on reality. Instead, the argument revealed how far some have drifted from it.
🚨 Ketanji ‘I’m Not a Biologist’ Jackson: “For cisGINGER girls, they can play consistent with their gender identity. For transgender girls, they can’t.” pic.twitter.com/uCqSHR6nM2
— Daily Caller (@DailyCaller) January 13, 2026
Justice Jackson attempted to frame the West Virginia law as internally inconsistent, suggesting it creates an overarching rule based on sex at birth while allowing “cisgender girls” to play consistent with their gender identity but barring “transgender girls” from doing so. In her telling, this amounted to unequal treatment. The problem with that framing is foundational. It treats “gender identity,” a subjective internal feeling, as a category equivalent to biological sex, which is an objective, observable fact.
Sex is not “assigned” at birth. It is observed. Doctors do not guess, speculate, or spin a wheel. They identify a biological reality that was determined long before birth. Yet Jackson repeatedly used the language of “assignment,” reinforcing the idea that sex is arbitrary rather than biological. That linguistic sleight of hand is doing enormous work in these cases, and it collapses under even minimal scrutiny.
West Virginia Solicitor General Michael Williams attempted to redirect the discussion, noting that the law does not target transgender athletes out of animus but instead preserves sex-based categories for reasons of fairness and safety. Jackson interrupted, returning to the notion that the case is really about redefining who qualifies as a “girl.” In doing so, she exposed the core dispute: whether the word “girl” still refers to a biological class or whether it has been emptied of meaning entirely.
🚨 BREAKING: DEI Justice Ketanji Jackson is DEFENDING men in women’s sports with an utter word salad at the Supreme Court
“Is treating someone transgender, but does not have, because of the medical interventions and the things that have been done, who does not have, uh, the… pic.twitter.com/QTkpru6EqO
— Eric Daugherty (@EricLDaugh) January 13, 2026
That confusion echoed in a separate exchange the same day, where Jackson floated the idea that medical interventions could eliminate relevant differences between males and females for athletic purposes. The ACLU’s attorney advanced a similar argument, claiming that if no “relevant physiological differences” exist, exclusion is unjustified. But biology does not disappear because someone wishes it away. Sexual differentiation begins in utero, is reinforced in early infancy, and continues through development. Suppressing puberty does not undo sex; it merely damages the body.
Justice Jackson’s reluctance to acknowledge these realities is not new. During her confirmation hearing, she famously declined to define “woman,” citing her lack of biological expertise. That admission alone raises an obvious question. If she is not equipped to define the category at issue, on what basis is she prepared to decide who belongs within it?
