What legal arguments did the Supreme Court majority and dissent use in the decision upholding state bans on transgender

Majority legal arguments

The bans are constitutional and lawful.
The six conservative justices held that the state bans do not violate the 14th Amendment’s equal protection guarantee [4].
They ruled that states may keep women’s and girls’ sports for biological females and decide eligibility based on biological sex. This approach, the majority said, is “consistent with Title IX and the Equal Protection Clause” [1] [5].

No overhaul of women’s sports required.
Writing for the majority, Justice Kavanaugh stated that neither the Constitution nor Title IX forces a fundamental re‑working of women’s and girls’ sports across the country [5].

Rejecting the dissent’s stance.
The majority opinion also pushed back against the dissent’s “assumed monopoly on understanding the effects on individuals” in these disputes [7].

Dissenting legal arguments

A “diminished” equal protection standard.
Justice Sotomayor, in her partial dissent, argued that the majority applied “a diminished view of equal protection” to sports, implying the analysis fell short of the proper constitutional scrutiny [6].

Procedural fairness denied.
The dissent said the majority inflicted a serious hardship on transgender athletes “without giving them the fair and full opportunity the Constitution requires to litigate their contentions” [2]. This is a due‑process or fairness‑of‑the‑process argument, not just a disagreement about the final result.

A narrow Title IX holding, perhaps unnecessary.
Justice Jackson’s partial dissent suggested the Court did not need to decide that Title IX protects against something (the exact quote from the evidence is truncated, so the full argument is unclear) [9].

How the Court interpreted Title IX

A unanimous bottom line.
Every justice agreed that the state bans do not violate Title IX, the federal law that prohibits sex‑based discrimination in schools [3].

The majority’s reading.
The majority interpreted Title IX as allowing states to base sports‑team eligibility on biological sex. The law’s purpose—to preserve and promote athletic opportunities for women and girls—does not, in its view, require including transgender women on women’s teams [1] [5].

Dissent’s silence on Title IX.
Because the Court was unanimous on the Title IX question, the dissent did not offer a competing Title IX interpretation. Instead, the dissenting justices focused on constitutional problems: equal protection, due process, and the proper scope of the Court’s holding.