Britain’s highest civil court ruled Wednesday that the definition of “woman” under the country’s gender equality law is based on a person’s sex at birth — a highly anticipated judgment in a case with implications for the protections of transgender people.

Trans women are not legally women under the Equality Act, the Supreme Court has ruled in a landmark judgment. Campaign group For Women Scotland (FWS) brought a series of challenges – including to the UK’s highest court – over the definition of “ woman ” in Scottish legislation mandating 50 per cent female representation on public boards.

The landmark ruling could have major implications for how sex-based rights apply across Scotland, England and Wales.