What's next for Caster Semenya?

The Court of Arbitration for Sport has rejected Caster Semenya's appeal against new rules for female athletes with unusually high testosterone levels.

It was a complicated verdict, though, leaving an uncertain future for both the track star and her sport. Let's unpack:

The background

If you're unfamiliar with Semenya or this fascinating, landmark case, we covered them in detail in this explainer:

To summarize, Semenya is a South African runner who has dominated the women's 800 metres for much of the last decade. She's won three world titles and the last two Olympic gold medals in that event.

Semenya has identified, and competed, as a woman her entire life. But her body naturally produces an unusually high level of testosterone for a woman. This is believed to be due to an intersex condition, meaning Semenya was born with a reproductive anatomy that doesn't fall neatly into the traditional buckets of male or female. She's not the only athlete with this trait, but she's the most high-profile.

More testosterone can help a person become stronger and faster, so track and field's world governing body (the IAAF) believes Semenya has an unfair advantage over other women. How much is still a matter of considerable scientific debate, but a year ago the IAAF went ahead with a new set of rules. They require female runners with what it calls "differences of sexual development" (DSD for short) to bring their testosterone below a certain level (it can be done with drugs) before they compete in women's events ranging from 400 metres to a mile. The IAAF said it was doing this to preserve fair and meaningful women's competition.

Semenya wants to continue running in her natural state, so she appealed on the grounds that the new rules are "discriminatory, unnecessary, unreliable and disproportionate." And today she lost that appeal.

The decision

The Court of Arbitration for Sport said in a press release that the full details of the decision will remain confidential for now, but it did provide the broad strokes. A panel of judges ruled 2-1 in favour of upholding the IAAF's testosterone restrictions, saying Semenya's side was "unable to establish that the DSD regulations were 'invalid.'" The court agreed that the new rules are discriminatory, but that "such discrimination is a necessary, reasonable and proportionate means of achieving the IAAF's aim of preserving the integrity of female athletics." 

This IAAF isn't off the hook, though

The judges expressed "serious concerns" about whether the rules can be applied fairly. They questioned how realistic it is for DSD athletes to always remain below the testosterone limit, and what would happen to someone who unintentionally exceeds it. They also doubt whether there's enough proof that elevated testosterone levels provide a significant advantage in the 1,500-metre and 1-mile races. So they suggested the IAAF hold off on applying the new rules to those events until it can gather more evidence (though that's only a suggestion: the IAAF can do what it wants).

More troubling, perhaps, is the issue of side effects to hormonal treatments. No one can really predict what will happen to an athlete who takes drugs to reduce her testosterone levels. Safety is a concern. The court said these potential consequences could make it practically impossible to enforce the new limits.

Interestingly, the CAS emphasized near the end of the press release that the DSD regulations are a "living document" — which it said were the IAAF's own words. So there's an expectation that adjustments will be made as needed. If not, the door could be open for more challenges to the rules.

So where does this leave track and field?

For now, pretty much the same. Now that the testosterone restrictions can go into effect starting May 8, there could be fewer people calling for radical changes. Some of the ideas floated included separate races for DSD athletes, or even dropping the binary men's and women's events. In that scenario, gender and sex wouldn't matter. Athletes would be classified according to their natural hormone levels and grouped accordingly — similar to how the Paralympics has many different divisions to account for varying disabilities.

However, track and field may have just robbed itself of one of its biggest stars. Which brings us to...

Where does this leave Semenya?

She has 30 days to appeal the CAS's decision to the Swiss Supreme Court, but only on limited grounds. Beyond that, there are only two options if she wants to continue her running career: suppress her testosterone in order to stay eligible for her best events, or find new events.

The latter option would mean something shorter than 400 metres or longer than a mile. The new rules don't apply to those. Interestingly, Semenya ran the first two IAAF-sanctioned 5,000-metre races of her career earlier this season, including a dominant victory at the South African championships. She also competed in a 200-m race for the first time in three years.

Those races are a stretch for her at the international level, though. She's had some success in the 1,500, winning bronze at the most recent world championships and gold at last year's Commonwealth Games, and also dabbled in the 400. But the new testosterone rules just so happen to extend to those — one of the reasons why Semenya's supporters say she's being unfairly targeted.

So how would she do if she conforms to the new regulations and keeps running her best events? Hard to say for sure, but it doesn't look good. A few years ago, the IAAF made its first attempt at restricting testosterone levels. It was eventually struck down, but in the meantime Semenya turned into a much slower runner. She didn't even qualify for the 2013 world championships, and failed to make the 800 final in '15. Other factors (injuries, say) could have been at play, and we don't know whether Semenya was taking testosterone-lowering drugs. But as soon as the restrictions were lifted, she blew away the field at the 2016 Olympics and '17 world championships.

The old limit, by the way, was 10 nanomoles of testosterone per litre of blood. The new one is even lower: five nanomoles.

There's one more meet before the new rules take effect

Track and field's premier series of events, the IAAF Diamond League, opens for the season on Friday in Doha. Semenya and another athlete with a testosterone condition, Francine Niyonsaba of Burundi, plans to compete in the 800. It's scheduled for 1:07 p.m. ET and you can watch it live on CBCSports.ca.

After that, everything could change for Semenya. But she sounded defiant today. "For a decade the IAAF has tried to slow me down, but this has actually made me stronger. The decision of the CAS will not hold me back," she said in a statement. "I will once again rise above and continue to inspire young women and athletes in South Africa and around the world."

This piece is an excerpt from The Buzzer, the CBC Sports daily newsletter. Subscribe below.