On Tuesday, the Supreme Court heard arguments on cases that could determine whether states have the authority to preserve women’s sports for biological females.

The cases, from Idaho and West Virginia, challenge laws that restrict girls’ and women’s athletic teams to participants of the same biological sex. Transgender students argue these laws violate Title IX and the Constitution’s Equal Protection Clause.

But beneath the legal claims lies a more fundamental question: who gets to define what it means to be a woman under the law?

The Court must decide whether government is required to treat self-declared gender identity as determinative—or whether it can rely on the objective reality of biological sex.

Upholding these laws protects fairness and safety in women’s sports. More importantly, it prevents sex (and womanhood itself!) from becoming an arbitrary legal construct.

That matters.