The United States Supreme Court has delivered a landmark ruling affirming a truth that should never have been in doubt: women’s sport exists for women and girls.

In West Virginia v. B.P.J. and Little v. Hecox, the Court upheld laws in West Virginia and Idaho requiring athletes to compete in sports categories aligned with their sex, not with their gender identity.

The 6-3 decision confirms that states may protect fairness, safety, and equal opportunity in women’s and girls’ sport.

Writing for the majority, Justice Brett Kavanaugh stated the principle plainly:

“Schools may determine eligibility for women’s and girls’ sports based on biological sex.”

The Court recognised that biological males generally possess physical advantages that matter in competitive sport, and that allowing males to compete in female categories can cost women and girls places on teams, medals, opportunities, and confidence to participate.

Justice Clarence Thomas’s concurring opinion went further, identifying the deeper cultural issue: the use of language to obscure reality. He wrote:

“Men and boys with gender dysphoria are not women or girls, even if they believe that they are. Sex is an immutable, ‘biological’ characteristic; it is binary; and ‘man’ and ‘woman’, ‘boy’ and ‘girl’, are the terms that correspond to adults and children of each sex. To use language to obscure reality – to show ‘indifference regarding the truth’ – is to lie to the public and cease to treat our fellow citizens ‘as equal[s]’.”

This decision matters beyond the United States.

In Australia, women, parents, teachers, doctors, and people of faith are increasingly pressured to deny biological reality or remain silent.

Those who speak plainly about sex and gender can face accusations of discrimination or harm simply for saying that men are not women and boys are not girls.

Compassion for people experiencing gender dysphoria does not require the erasure of women. Dignity for every person does not require dishonesty. A fair society can respect individuals while still recognising the reality of sex. A just society must recognise the real distinctions between male and female and protect the rights and dignity of women and girls.

Women’s sport, and women’s rights more broadly, depends on that truth. So do freedom of speech, freedom of conscience, and the ability of parents and faith communities to live according to their convictions.

The Supreme Court’s ruling is a welcome reminder that truth is not unjust discrimination. Law must remain tethered to reality, because justice cannot be built on a lie.