The Court of Arbitration of Sport Ruling is well worth reading.
www.tas-cas.org/fileadmin/user_upload/CAS_Executive_Summary__5794_.pdf?fbclid=IwAR0D_yFNIGmgcByO7PpwXIxuhIj0W6YzfeOVnuou9B8RIclp_Bsmrwkj8QE
"Accordingly, the purpose of the male-female divide in competitive athletics is not to
protect athletes with a female legal sex from having to compete against athletes with a
male legal sex. Nor is it to protect athletes with a female gender identity from having to
compete against athletes with a male gender identity. Rather, it is to protect individuals
whose bodies have developed in a certain way following puberty from having to compete
against individuals who, by virtue of their bodies having developed in a different way
following puberty, possess certain physical traits that create such a significant
performance advantage that fair competition between the two groups is not possible. In
most cases, the former group comprises individuals with a female legal sex and a female
gender identity, while the latter group comprises individuals with a male legal sex and
male gender identity. However, this is not true of all cases. Natural human biology does
not map perfectly onto legal status and gender identity. The imperfect alignment between
nature, law and identity is what gives rise to the conundrum at the heart of this case."
"It was common ground between the parties that there is a substantial difference in elite
sports performance between males and females. It was also common ground that (a) the
normal female range of serum testosterone, produced mainly in the ovaries and adrenal
glands, is 0.06 to 1.68 nmol/L; and (b) the normal male range of serum testosterone
concentration, produced mainly in the testes, is 7.7 to 29.4 nmol/L. On the basis of the
scientific evidence presented by the parties, the Panel unanimously finds that endogenous
testosterone is the primary driver of the sex difference in sports performance between
males and females."
"Having carefully considered the expert evidence, the majority of the Panel concludes that
androgen sensitive female athletes with 46 XY DSD enjoy a significant performance
advantage over other female athletes without such DSD, and that this advantage is
attributable to their exposure to levels of circulating testosterone in the normal adult male
range, rather than the normal adult female range. The majority of the Panel observes that
the evidence concerning the performances and statistical over-representation of female
athletes with 46 XY DSD in certain Relevant Events demonstrates that the elevated
testosterone levels that such athletes possess creates a significant and often determinative
performance advantage over other female athletes who do not have a 46 XY DSD
condition."