Caster Semenya is once again free to run the 800m without having to take medication – at least for the time being – after the Swiss supreme federal court ordered the IAAF to suspend its testosterone regulations for her with immediate effect.

The surprise news – which completely blindsided athletics’ governing body – means that the Olympic champion can compete in distances ranging from 400m to a mile without medication until at least 25 June. However, for now it applies only to the South African and not other athletes with differences in sexual development (DSD).

‘The IAAF will not drug me or stop me being who I am’: Semenya appeals against Cas ruling Read more

Semenya’s lawyer, Greg Nott, who hailed the decision as “morally uplifting and so good for Caster”, revealed that his team had asked for the suspension when they appealed against the court of arbitration for sport’s ruling in Semenya’s case last week.

“The court has ordered the IAAF to suspend immediately the implementation of the regulation with regard to Caster and has given the IAAF until 25 June to respond to the suspense of effect,” said Nott. “It is absolutely positive news.”

In a short statement Semenya thanked the Swiss judges for their decision. “I hope that following my appeal I will once again be able to run free,” she added.

Her Swiss counsel, Dr Dorothee Schramm, also welcomed the decision. “This is an important case that will have fundamental implications for the human rights of female athletes,” she said.

The ruling is the latest twist in the dispute between Semenya and the IAAF over a policy which requires DSD athletes to reduce their testosterone to below five nmol/L for at least six months if they want to compete internationally at all distances from 400m to a mile.

Last month Cas accepted such a policy was “discriminatory” to DSD athletes, who are usually born with testes. However, it ruled in favour of the IAAF after accepting its argument that high testosterone in female athletes confers significant advantages in size, strength and power from puberty onwards.

In its decision Cas said the policy was “necessary, reasonable and proportionate” to ensure fair competition in women’s sport.

The impact of that decision was immediate. Last week in Stockholm a Diamond League women’s 800m race was won by a non-DSD athlete – the American Ajee Wilson – for the first time since 2015. Semenya and the Burundi athlete Francine Niyonsaba had won the last 22 races.

Now, however, the case could drag on for months without a resolution – and it could yet mean that the South African is able to defend her world 800m title in Doha in September.

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When asked for a response to the suspension and the likelihood of what could happen next, the IAAF issued the following statement: “We have received no information from the Swiss federal court so we cannot comment at this stage.”

However. Monday’s ruling has encouraged Semenya’s team that the Swiss federal supreme court could set aside Cas’s decision in its entirety. They argue that the IAAF’s policy is unfair and unnecessary, and say unwanted hormonal drug interventions could have uncertain health consequences on athletes.

Semenya is supported by the World Medical Association, which has declared the IAAF regulations to be contrary to their basic ethical principles. When she launched her appeal last week, she again insisted that she would not take medication to reduce her testosterone. “I am a woman and I am a world-class athlete,” she said. “The IAAF will not drug me or stop me from being who I am.”

The South African is expected to compete in a 2,000m race next week in Paris and then a 3,000m race at the Prefontaine Classic on 30 June. However, she may now decide to have an immediate crack at another 800m – an event in which she is unbeaten since 2015.