Caster Semenya competes in the 1,500 meters at a meet in Johannesburg last month. (AFP/Getty Images) (Stringer/AFP/Getty Images)

Who is Caster Semenya?

Semenya, 28, is a South African middle distance runner and two-time Olympic gold medalist at 800 meters. She has also won gold at that distance at three world championships.

What is the issue?

Semenya is thought to have an intersex condition known as hyperandrogenism, which means her body may naturally produce androgens — male sex hormones that include testosterone — at higher levels than most women. Many in the track and field community are concerned that Semenya has an unfair advantage over competitors because of her naturally occurring high level of testosterone.

What is testosterone?

Testosterone is a hormone produced by both men and women, but at higher levels in most men. It increases muscle mass, strength and hemoglobin, which can enhance endurance. Testosterone is a banned substance when administered from outside the body, but Semenya is thought to produce her level of testosterone naturally. As an Olympic and world champion, she has been drug tested many times and has never tested positive for a banned substance.

Who are the parties involved?

The International Association of Athletics Federations (IAAF) is the world governing body for track and field. The Court of Arbitration for Sport (CAS) is an independent international body established to settle disputes in sport.

How did this suit come about?

In 2009, when she was 18, Semenya won the 800 at the world championships and was forced to submit to a gender test based largely on her appearance, her fast times and mounting speculation around track. In 2011, the IAAF introduced a new measure — its Hyperandrogenism Regulations — that put a cap on testosterone levels and required some women to take hormone-suppressing drugs to compete. But in 2015 the CAS ordered that rule to be suspended and eliminated any ceilings on acceptable testosterone levels in female competitors. The court also gave the IAAF time to study the science and revisit the matter.

In April 2018 the IAAF announced it was reinstituting a cap on permissible testosterone levels for certain events — 400-, 800- and 1,500-meter races, the same distances in which Semenya regularly competes. That rule was supposed to go into effect in November of last year but was delayed pending the CAS ruling. Semenya’s attorneys argued her case at the CAS in Lausanne, Switzerland, in February, and the court promised a ruling in March, but that was pushed back until May 1.

What are the arguments?

The IAAF says to ensure a level playing field, no female competitors can have heightened testosterone levels. While acknowledging these increased levels are naturally occurring and could be a result of a Difference of Sexual Development (DSD), the organization suggests they could improve performance by 5 percent or more. The proposed rule would require women classified as having DSD to reduce their testosterone level to below 5 nmol/L for six months before they can compete, and they must maintain that continuously.

Semenya’s attorneys called the rule “discriminatory, irrational, unjustifiable.” And Semenya, who says little about the issue despite becoming a lightning rod for the controversy, said the rules continue “the offensive practice of intrusive surveillance and judging of women’s bodies which has historically haunted women’s sports.”

What did the court rule?

The court announced Wednesday morning that Semenya will be forced to medicate to suppress her testerone levels. By a 2-1 vote, the judges ruled that “on the basis of the evidence submitted by the parties, such discrimination is a necessary, reasonable and proportionate means of achieving the IAAF’s aim of preserving the integrity of female athletics in the Restricted Events.” But the court said the IAAF should not yet apply the rules to the 1,500.

The court also ruled that the IAAF’s proposed rules on athletes with DSD are discriminatory.

Semenya reacted Wednesday morning on Twitter, saying, “Sometimes it’s better to react with no reaction.”

What happens next?

The next major international competition is the IAAF’s world championships, which begin in late September in Doha, Qatar. Semenya will have to lower her testosterone levels to compete.