The UK Supreme Court is to deliver its verdict on how a woman should be defined in law.
The announcement marks the culmination of a long-running legal battle between the Scottish government and a women's group.
The outcome could have far-reaching implications on how sex-based rights apply across Scotland, England and Wales.
The Scottish government argues transgender people with a gender recognition certificate (GRC) are entitled to sex-based protections, while For Women Scotland argues they only apply to people that are born female.