The UK’s Supreme Court has ruled that “man”, “woman” and “sex” in the Equality Act 2010 refer to sex, not self-ID or paperwork (gender-recognition certificates). This agreed with our legal interpretation. We have published new guidance and are in the process of updating our publications to reflect the judgment. We are also working to provide answers to the questions we're hearing from supporters and the media. We will publish these as soon as possible.

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Stephen O’Rahilly

Professor of clinical biochemistry and medicine

@StephenORahilly

Stephen is professor of clinical biochemistry and medicine at the University of Cambridge and an honorary consultant physician at Addenbrooke’s Hospital, Cambridge. He is a graduate of University College Dublin medical school and, after post-graduate training in general medicine and endocrinology in London, Oxford and Harvard, set up his lab at the University of Cambridge in 1991. His research has discovered the fundamental mechanisms underlying many inherited metabolic and endocrine disorders. Such discoveries have led to patient benefit through improved diagnosis, targeted therapies and the development of national specialist services. 

He played a leading role in the establishment of the Institute of Metabolic Science at the University of Cambridge and was its founding co-director: it is now one of the world’s leading multi-disciplinary centres for the study of metabolic diseases. His work has been recognised by numerous prestigious awards, including fellowship of the Royal Society and foreign membership of US National Academy of Sciences. In 2013 he was knighted for services to medical research.

“I am concerned about the conflation of sex and gender in public discourse for a number of reasons.

  1. As a medical doctor and endocrinologist I have long been concerned that the evidence base for the use of hormonal and surgical treatments for gender dysphoria is very weak and that the use of such powerful, permanently life-altering therapies should be much more rigorously evaluated and tightly regulated. 

    I am also very aware of how the three periods of high androgen exposure (inta-uterine, post-natal and pubertal) to which biological males are exposed have profound and irreversible effects on development and anatomy. In contrast to the gametic, chromosomal, hormonal and anatomical aspects of sex, each of which can be meaningfully assessed, I do not believe that it is possible to define gender identity as a stable and measurable trait.
  1. As a scientist I am very aware of the centrality of sex to the understanding of the evolution and fundamental functioning of our own and many other species. Losing the meaning of sex is detrimental to rational scientific discourse. 
  1. As a human being I have been horrified to see many societies prioritise the feelings of a small number of men wishing to present as women over the safety and dignity of women, particularly those in vulnerable situations such as prisons, hospital wards, rape-crisis centres and domestic-abuse shelters. I am also very concerned about the widespread persecution of those who make factual statements about sex versus gender.
  1. As a sports enthusiast, I am very concerned about the unfairness of allowing male-bodied people to compete with females in sports where the physical advantages of having developed under the influence of high testosterone are abundantly clear.”