The United Kingdom's top court on Wednesday upheld an appeal by a campaign group on whether transgender women are legally women under equality legislation, ruling that the law referred to a "biological woman and biological sex".

The Supreme Court's judgment related to whether a trans woman with a gender recognition certificate (GRC), a formal document which gives legal recognition of someone's new gender, is protected from discrimination as a woman under Britain's Equality Act.

Campaign group For Women Scotland had argued those rights should only apply based on a person's biological sex, and had challenged guidance issued by the devolved Scottish government over a 2018 law that was designed to increase the proportion of women on public sector boards.

Scottish ministers' guidance on that law stated that a trans woman with a full GRC was legally a woman.

"The terms women and sex in the Equality Act 2010 refer to a biological woman and biological sex, but we counsel against reading this judgment as a triumph for one or more groups in our society at the expense of another – it is not," Patrick Hodge, deputy president of the Supreme Court. (Reuters)