"The Swiss-based Court of Arbitration for Sport addressed a complicated, highly charged question involving fair play, gender identity, biology and human rights... Since competition is divided into male and female categories, what is the most equitable way to decide who should be eligible to compete in women’s events?"

"Restrictions on permitted levels of naturally occurring testosterone are discriminatory, the court ruled Wednesday in a 2-to-1 decision. But, the panel added, such discrimination is a 'necessary, reasonable and proportionate means' of achieving track and field’s goal of preserving the integrity of women’s competition.... The [International Association of Athletics Federations] had argued that athletes classified with 'differences of sexual development' — particularly those who possess testes and natural testosterone levels in the male range — gain an unfair advantage in women’s events from 400 meters to the mile in terms of additional muscle mass, strength and oxygen-carrying capacity.... [Caster Semenya's] lawyers said in a statement that they might appeal Wednesday’s decision, arguing that 'her unique genetic gift should be celebrated, not regulated.' The I.A.A.F. accepts athletes with differences of sexual development as legally female. For competitive purposes, though, it effectively considers them biologically male. And now the federation has been given the go-ahead to put in place a rule requiring these athletes to medically limit their testosterone levels in certain women’s events that synthesize speed, power and endurance. This is necessary to provide a level playing field in races that can be won by a margin as small as a hundredth of a second, the I.A.A.F. contends. To do nothing, it has said, risks 'losing the next generation of female athletes.'"

From "Court Bars Women With High Testosterone From Some Track Races" (NYT).

Most women, including elite athletes, have natural testosterone levels of 0.12 to 1.79 nanomoles per liter, the I.A.A.F. said, while the normal male range after puberty is much higher, at 7.7 to 29.4 nanomoles per liter. No female athlete would have natural testosterone levels at five nanomoles per liter or higher without so-called differences in sex development or tumors, the I.A.A.F. has said.

Doriane Lambelet Coleman, a law professor at Duke and an elite 800-meter runner in the 1980s who served as an expert witness for the I.A.A.F., wrote in The New York Times in April 2018 that “advocates for intersex athletes like to say that sex doesn’t divide neatly.” She continued: “This may be true in gender studies departments, but at least for competitive sports purposes, they are simply wrong. Sex in this context is easy to define and the lines are cleanly drawn: You either have testes and testosterone in the male range or you don’t.... There is no characteristic that matters more than testes and testosterone.”...

Athletes transitioning from male to female must declare that their gender identity is female and cannot rescind that declaration for a minimum of four years for sporting purposes. The athletes must also suppress their testosterone level below 10 nanomoles per liter for a year before becoming eligible for the Winter or Summer Games. The ruling in the Semenya case, though, is expected to prompt the I.O.C. to recommend that all Olympic sports adopt the more restrictive cutoff of five nanomoles per liter.

This is a complicated problem. Keep the facts straight: Semenya's condition is inborn. She is not transgender. She did not transition. She wants to compete, in the women's division of sports, with her natural level of testosterone, and will need to use artificial means to suppress that testosterone to 5 nanomoles per liter, which is still much higher than what "[m]ost women, including elite athletes" have. Other athletes, who are "male to female" transgender must also suppress their testosterone to compete in the Olympics as women, and they've only had to get below 10 nanomoles. That's expected to change to 5, now that Semenya is required to get to 5.

I'm interested in this concept of "preserving the integrity of women’s competition," but what does that mean, exactly? It seems like: preserving the public's interest in the separate, easier division of sports that we created for women.