Single-sex spaces open to the public, such as toilets and changing rooms, should be organised based on biological sex, according to official guidance that has come into force. It comes 16 months after the UK Supreme Court ruled "sex" in equality law means "biological sex" rather than the gender someone identifies as. Trans-rights campaigners have called the guidance unworkable, but groups that campaign for sex-based rights welcome the clarity it brings. The Equality Act provides protections for people on the grounds of both biological sex and gender reassignment. In response, campaigners including some women's and gay rights groups say this undermines sex-based protections, particularly for women.