I've come to the conclusion that nothing short of returning to a baseline definition of females as being persons with XX chromosomes, female genitals and female gonads will do.
The definition will specify which edge cases fall within the female boundary for the purposes of participating in female sports. This could be a rule stating that athletes must meet at least two out of these three characteristics, which is how sex is defined and edge cases delineated in UK law (sex is the combination of chromosomes, genitals and gonads. To qualify as a member of one sex a person must have at least any two of these).
I actually thought that this was the general definition used for sports purposes, but reading a recent thread on Ovarit, I was wrong.
Here is the comment by a poster called ProxyMusic that explains what happened:
Yes, the insulting, misogynistic & male supremacist practice of using testosterone levels to determine eligibility for female sports was started by XY DSD athletes who objected to, & sued over, the IOC's & IAAF's use of Barr body buccal swab sex chromosome testing to determine eligibility for female events - a practice in place for circa 30 years from the mid 1960s to mid/late 1990s.
The athlete you are speaking of is Maria José MartÃnez-Patiño, born 1961, a Spanish hurdler who was intially disqualified from women's athletics when found to be XY & successfully sued to be re-instated. It's because of that case that sports governing bodies began to redefine women according to male standards. Instead of being defined as human beings with female sex chromosomes, female gonads & female reproductive systems, women were redefined in sports as persons of any sex chromosomes, any kind of gonads, & any kind of repro anatomy who met any or all of the following criteria:
absent male external genitalia, or male genitalia that malformed in utero;
natural testosterone produced by testes that's lower than & outside the normal male range;
normal male levels of testosterone made by testes, but a lowered or lack of ability to make use of T as males typically do because of male androgen receptors that don't function properly.
In other words, the categories "women" & "female athletes" now came to include males with male-only DSDs that resulted in them having missing, undersized and/or misshapen penises, along with testes that were undescended at birth but still work properly, producing far more testosterone than females ever could - & in many cases producing viable sperm capable of enabling these athletes & so-called "women" to father children.
Not coincidentally, Maria José MartÃnez-Patiño was one of the 20 people at the IOC who decided in 2015 to allow males to compete in women's Olympics so long as the males declare they have a "female gender identity" at least "for sporting purposes," & can demonstrate that for 12 months prior to entering a women's event their T levels have been below 10 nmol/L - a level well within the normal male range, BTW.
As it turns out, there were only four actual female people on the IOC subcommittee that decided to open up female sports to males using claims of "gender identity" in 2015. The rest of the committee consisted of 14 XY persons without DSDs, one XY with a DSD, & one TIM, the TRA Joanna Harper. Given that TIMs & XY DSD persons constitute a teeny-tiny proportion of the population, whilst girls & women constitute 51%, it seems to me that females were vastly under-represented on the IOC committee that did away with female-only sports - whilst TIMS & XY DSD athletes were vastly over-represented.
Thanks to those male athletes suffering from male-only DSDs we have had male sports and mixed sports for decades. That Ovarit thread is right, we need to stop talking about hormones and return to defining men as male and women as female and segregate our sports categories strictly by sex.