The Supreme Court has announced that the definition of a woman is based on biological sex in a landmark judgement.

Lord Hodge said that five Supreme Court justices had unanimously decided that ‘the terms woman and sex in the Equality Act refer to a ‘biological woman and biological sex’.

He recognised ‘the strength of feeling on both sides’ and cautioned against seeing the judgement as a triumph for one side over another, stressing that the law still gives trans people protection against discrimination.

In an 88-page ruling, the justices said: ‘The definition of sex in the Equality Act 2010 makes clear that the concept of sex is binary, a person is either a woman or a man.’

The decision could have far-reaching implications on how sex-based rights apply, including how women-only spaces are allowed to operate.

Conservative leader Kemi Badenoch praised the ruling as a ‘victory’ for women and said it meant the ‘era of Keir Starmer telling us women can have penises has come to an end’.

The judgement marks the culmination of a long-running legal battle between the Scottish government and a women’s group over the definition of a ‘woman’ in Scottish legislation mandating 50 per cent female representation on public boards.

The case centred on whether somebody with a gender recognition certificate (GRC) recognising their gender as female should be treated as a woman under the 2010 Equality Act.