The legal case How Scottish action will echo across Great Britain

The narrow point of law on which the court has been asked to rule is who counts as a woman under the UK's Equality Act, and whether that legal definition includes transgender women possessing a gender recognition certificate (GRC).

- Libby Brooks

Although the court battle began in Scotland, the ruling, expected today, could have implications for how single-sex spaces and services are run in England, Scotland and Wales.

Today's judgment concludes court action by For Women Scotland (FWS) over Holyrood's Gender Representation on Public Boards (Scotland) Act 2018, which was aimed at improving gender balance. An amendment to the SNP government's bill, brought by a Scottish Labour MSP, expanded the scope of the legislation to include all trans women, whether or not they had applied for a GRC.

FWS launched a judicial review, arguing that Holyrood had gone beyond its competence by using such a wide definition of "woman" and the inner court of session in Edinburgh agreed.

Scottish ministers revised the statutory guidance, which stated the new law would follow the Equality Act by including transgender women who had a GRC within the definition of "woman".

FWS launched another judicial review, which was dismissed, and after further appeals brought the case to the supreme court.

Its crowdfunder has so far raised £230,000, including £70,000 donated by the Harry Potter author and activist JK Rowling.