J.K. Rowling, the author of the Harry Potter series, has publicly celebrated the U.K. Supreme Court’s recent decision defining “woman” based on biological sex. The ruling, delivered on April 16, clarified that under the Equality Act 2010, the terms “woman” and “sex” refer exclusively to biological distinctions, thereby excluding transgender women from this legal definition. ​

Rowling, a vocal advocate for women’s rights, expressed her support for the judgment on social media, stating, “It took three extraordinary, tenacious Scottish women with an army behind them to get this case heard by the Supreme Court and, in winning, they’ve protected the rights of women and girls across the U.K.”

The Supreme Court’s unanimous decision stemmed from a case brought by the group For Women Scotland, which challenged the inclusion of transgender women with Gender Recognition Certificates in the legal definition of women for public sector board quotas. The...