Christine Mboma, won a silver medal at the 2021 Olympics in the women’s 200m track. Her advantage comes from being an athlete with differences in sex development (DSD). The Court of Arbitration for Sport (CAS) now has a wicked dilemma when it comes to protecting women’s sport.

Francine Niyonsaba, who won the women’s 5000m Diamond League final, is another athlete with DSD. Athletes with DSD are banned from certain events such as the 400m and one mile run, but can still compete in other events. World Athletics is now facing pressure to become more consistent.

Crucially, CAS ruled that 46 XY DSD athletes “enjoy a significant sporting advantage … over 46 XX athletes without such DSD” due to biology.

It noted that 46 XY 5-ARD [5-alpha reductase deficiency] individuals have male testes but do not produce enough of a hormone called DHT, critical for the formation of male external genitalia, which it said leads to having “no typical birth sex”.

However, it added: “Individuals with 5-ARD have what is commonly identified as the male chromosomal sex (XY and not XX), male gonads (testes not ovaries) and levels of circulating testosterone in the male range (7.7-29.4 nmol/L), which are significantly higher than the female range (0.06-1.68 nmol/L).”

Advantages are not just derived from testosterone production. Experts from both sides have identified other advantages, including “greater lean body mass, larger hearts, higher cardiac output... and larger V02 max than 46 XX individuals”.

The question now is how to make sport fair for women.

Essentially the argument boils down to whether you value fairness or inclusivity more. Either way, critics on both sides believe World Athletics’ current policy is not fit for purpose. (because the rules are not across the board)

As CAS  noted in the Semenya case – it involves incompatible and competing rights.

“Put simply, on one hand, is the right of every athlete to compete in sport, to have their legal sex and gender identity respected, and to be free from any form of discrimination,” it said.

“On the other hand, is the right of female athletes, who are relevantly biologically disadvantaged vis-à-vis male athletes, to be able to compete against other female athletes and to achieve the benefits of athletic success.”

Binary spokeswoman, Kirralie Smith, said it is a critical issue to resolve.

“Being male is not just determined by testosterone levels, it is evidenced by chromosomes, gamete production, hormone production and reproductive organs,” she said.

“These athletes with DSD have more biological male traits, than female ones. Most governing bodies in sport and politics refuse to define the terms man and woman, male or female.

“Instead of biological reality they now appease activists according to feelings or identity. It is blatantly unfair, and in some cases unsafe, for biological females.”