The United Kingdom’s highest court ruled that the legal definition of “woman” excludes trans women, in a case with sweeping consequences for how equality laws are applied.

The decision could have far-reaching implications for the protections and freedoms given to transgender women in the U.K.

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.