Features 19 June 2018

Semenya challenges DSD regulations at CAS

South African athlete Caster Semenya has challenged the International Association of Athletics Federations (IAAF) Differences of Sex Development (DSD) Regulations at the Court of Arbitration for Sport (CAS). ‘Caster Semenya seeks a ruling from CAS to declare such regulations unlawful and to prevent them from being brought into force’, reads a statement. 

The DSD Regulations (PDF below) regulate athletes with one of seven listed differences in sex development competing in international events run between 400m and one mile in the IAAF’s female category, if the testosterone they produce is above 5nmol/L and has an ‘androgenising effect’ (i.e. if it is taken up by their androgen receptors and boosts their physiology). The IAAF contends that athletes covered by the DSD Regulations who produce testosterone at above 5 nmol/L have such a significant performance advantage over other females that they should be required to take testosterone suppressing medication for six months before they can compete in the Restricted Events. 


Caster Semenya is a successful middle distance runner who has won gold in the 800m at the London 2012 and Rio 2016 Olympics. She also won gold in the 800m and 1,500m at the Gold Coast 2018 Commonwealth Games. 

In 2011, the IAAF introduced its Hyperandrogenism Regulations – its first set of Regulations based on the idea that higher levels of testosterone produced by some females gave them an advantage over other females – after outrage at gender tests being conducted on Semenya, then 19, after she won 800m gold at the IAAF Berlin World Championships in 2009. “She is a woman, but maybe not 100%”, Pierre Weiss, General Secretary of the IAAF, told media at the time.

“It is not fair”, Semenya told the BBC yesterday. “I just want to run naturally, the way I was born. I am Mokgadi Caster Semenya. I am a woman and I am fast.”

Semenya will be represented at CAS by Norton Rose Fulbright. ‘Caster Semenya will file the legal challenge to ensure, safeguard and protect the rights of all women on the basis that the Regulations are irrational, unjustifiable, and in violation of the IAAF Constitution (based in Monaco), the Olympic Charter, the laws of Monaco, the laws of jurisdictions in which international competitions are held, and of universally recognised human rights’, read a statement from the law firm.

Basis for the DSD Regulations

The basis for the DSD Regulations is that athletes who have one of seven DSDs listed by the IAAF have such an advantage from the extra testosterone they produce that it is necessary to exclude them from races run between 400m and one mile in the female category. The reason it sets the limit at 5 nmol/L is set out in the Explanatory Notes to the DSD Regulations (PDF below). Click here for a more detailed discussion, and click here for an IAAF response.

In the Explanatory Notes, the IAAF contends that ‘increasing testosterone levels in women from 0.9 nmol/L to just 7.3 nmol/L increases muscle mass by 4% and muscle strength by 12-26%, while increasing it to 5, 7, 10 and 19 nmol/L respectively increases circulating haemoglobin by 6.5%, 7.8%, 8.9% and 11% respectively. Taking all available knowledge and data into account, the experts estimate that the ergogenic advantage in having circulating testosterone in the normal male range rather than in the normal female range is greater than 9%.’

The basis for this claim is a 2018 Study, ‘Circulating Testosterone as the Hormonal Basis of Sex Differences in Athletic Performance’, which is yet to be published by Endocrine Reviews. The authors of the study are Professor David Handelsman of the University of Sydney, Professor Angelica Hirschberg of Karolinska Institutet and Dr. Stéphane Bermon, the IAAF’s Head of Science and Health. 

The IAAF has admitted that this Study involves instances where athletes were given exogenous testosterone and the effects on performance were measured. “At lower levels, they’ve managed to dose females”, Jonathan Taylor, who drafted the DSD Regulations for the IAAF, told The Sports Integrity Initiative. “I don’t know how they got ethical approval, but they did. It shows that if you go from a female range to a male range, from 0.2 nmol/L to 7 nmol/L – the lower standard of the male range – there is an increase in muscle mass and strength.

“But even better than that, a couple of research papers that are nothing to do with the IAAF, show endogenous testosterone and the increase in haemoglobin. And the increase in haemoglobin if you go from the female range to the lower end of the male range – in a female with DSD – it is something like 8%. That’s the bottom end.”

Question one – testosterone levels

Testosterone is an anabolic steroidal hormone produced by XY men in large amounts and XX women in smaller amounts. It is understood that the human physiology processes it in the same way, irrespective of how it arrives into an athlete’s physiology. 

It is understood that this is why it has been so effective as a doping substance. An athlete that takes on exogenous (external) testosterone will display increased muscle and bone mass upon exercise, as their physiology is processing additional anabolic steroidal hormones that they did not produce. It is understood that exogenous testosterone has been so successful in doping female athletes because they produce less testosterone to start with, so a small increase will produce a more marked effect.

The Study that underpins the DSD Regulations’ contention that athletes who produce testosterone at above 5 nmol/L enjoy a significant advantage in the restricted events involves giving athletes exogenous testosterone. That is not what the DSD Regulations seek to regulate. They regulate testosterone produced by an athlete, not exogenous testosterone that is added to their physiology in order to take their levels to above 5 nmol/L.

To be fair to the IAAF, stimulating an athlete into producing testosterone at above 5 nmol/L through eating the correct foods etc. would be almost impossible. Whether the CAS will examine whether the Study’s methodologies and the subject of the Regulations are compatible remains to be seen.

Question two – degree of advantage

When they were published, the Explanatory Notes to the IAAF’s DSD Regulations argued that women who have testosterone that falls within the male range enjoy an advantage of 9%. The IAAF argues that a similar advantage is also held by athletes with one of the seven DSDs who produce testosterone at above 5 mol/L, and therefore intervention is necessary in order to protect other female athletes from unfair competition in the Restricted Events.

However, as the Explanatory Notes explain, the IAAF’s Study involves giving exogenous testosterone, in other words additional testosterone to that which is produced by their physiology, to women in order to take their levels up to 7.3 nmol/L. And the 9% advantage involves testosterone that falls within the ‘normal male range’, which it gives as above 7.7 nmol/L. 

As mentioned, the limit for athletes with one of the seven DSDs identified by the IAAF is 5 nmol/L. Therefore, it would appear logical that the advantage in the Restricted Events held by DSD athletes who produce testosterone at above 5 nmol/L is likely to be less than 9%. In a statement issued today, the IAAF acknowledges that the degree of advantage in the Restricted Events enjoyed by a female athlete with a DSD, who produces testosterone at above 5 nmol/L, is likely to be between 5% and 6%.

‘Sex differences in physical attributes such as muscle size and strength and circulating haemoglobin levels give male athletes an insurmountable competitive advantage over female athletes in sports where size, strength and power matter’, it reads. ‘These advantages (which translate, in athletics, to an average 10-12% performance difference across all disciplines) make competition between men and women as meaningless and unfair as an adult competing against a child or a heavyweight boxer competing against a flyweight. Only men would qualify for elite-level competition; the best female athlete would not come close to qualifying.

‘The evidence gathered by the experts consulted by the IAAF (both peer-reviewed research and observational data from the field) suggests that having levels of circulating testosterone in the normal male range rather than in the normal female range, and being androgen-sensitive gives a female DSD athlete a performance advantage of at least 5-6% over a female athlete with testosterone levels in the normal female range (which is an enormous difference in events where milliseconds count). The effects are most clearly seen in races over distances between 400m and one mile, where the combination of increased lean body mass and elevated circulating haemoglobin appears to have the greatest combined impact.’

In the Dutee Chand judgment, the CAS found that the Indian sprinter was ‘unsuccessful in her challenge to the underlying scientific basis of the Hyperandrogenism Regulations’ because the Panel was ‘satisfied, to the requisite standard of proof, that there is a scientific basis in the use of a testosterone as a marker for the purposes of the Hyperandrogenism Regulations’. 

In other words, the CAS accepted that the IAAF can use testosterone produced by athletes as a basis to form regulations on eligibility for female competition. But it also found that the IAAF must demonstrate that the advantage provided by that testosterone is significant enough to warrant exclusion of some athletes.

In the Chand case, the IAAF argued that ‘men have significant advantages in size, strength and power over women, due in large part to men’s higher levels of circulating testosterone from puberty onwards’. As its statement repeats today, it puts the advantage that men have over women at between 10% and 12%.

The CAS Panel found that ‘the evidence does not go so far as to equate, or correlate, the level of testosterone in females with a percentage increase in competitive advantage. The evidence does not, for example, establish an advantage of the order of 12% rather than, say 1% or 3%. Once the degree of competitive advantage is established, the IAAF would then need to consider, if the degree of advantage were well below 12%, whether that justified excluding women with that advantage from the female category.’

That appears to be the stage we are at now. The IAAF Study in support of its DSD Regulations has not been published, but it argues that athletes with a DSD who produce testosterone at above 5 nmol/L have an advantage over other females of above 5% to 6%, but under 9%. Whether a CAS Panel will accept that the evidence in the IAAF’s Study is sufficient to support the idea that underpins the DSD Regulations, that such an advantage exists and is unfair, remains to be seen.

Whether the testosterone levels of females who do not have one of the seven DSDs outlined by the IAAF in its Regulations have been measured – for comparative purposes – is unknown. Whether the IAAF has measured whether the degree of advantage provided by testosterone levels of above 5 nmol/L in the Restricted Events is greater than that enjoyed by a woman with – for example – greater lung capacity, is also unknown. 

The IAAF has recognised such issues, but argues that the degree of advantage enjoyed by DSD athletes who produce testosterone at levels above 5 nmol/L in the Restricted Events is so great that regulation is necessary. It also hints that such an advantage is unnatural, as opposed to height, which it describes as a ‘natural’ advantage.

‘There is no other genetic or biological trait encountered in female athletics that confers such a huge performance advantage’, it argues in its Explanatory Notes. ‘If height were deemed to confer an unfair advantage in a particular event, then it might become appropriate to introduce height classifications. Until then, however, it is appropriate to treat such ‘natural’ advantages differently from the advantage that a female athlete with a DSD gets from her elevated levels of circulating testosterone.’ 

Question three – jurisdiction

Clause 5 of the DSD Regulations requires all disputes relating to the DSD Regulations to be settled via arbitration at the CAS. The IAAF argues that this is because as sports rules apply globally, ‘it is critical to obtain a definitive ruling from one authoritative body, rather than a range of different decisions from different courts and tribunals across the globe, which would lead to uneven application of the rule and so deny athletes a level playing field’.

The CAS was set up to arbitrate sporting disputes for the very reasons outlined above. It will therefore have no trouble assessing whether the DSD Regulations are in violation of the IAAF Constitution or the Olympic Charter, as outlined in Norton Rose Fulbright’s statement. However, it will be interesting to see how the CAS Panel approaches the questions as to whether the DSD Regulations violate the laws of Monaco, other jurisdictions where international competitions are held, and universally held human rights principles.

If the CAS Panel rules that the DSD Regulations are compatible with international laws and human rights principles, what happens if Semenya’s legal team disagrees? The Human Rights Tribunal of Ontario has already ruled that policies in this area that originated from the International Olympic Committee (IOC) have infringed the human rights of Kristen Worley. Could the IAAF find itself in a human rights court?

“This is a landmark case concerning international human rights and discrimination against women athletes with major consequences for gender rights which are jealously protected by the South African Bill of Rights”, says Greg Nott, who is leading Semenya’s legal team, in a statement. “We are honoured to represent Ms Semenya and advance a position that protects all affected women”.


The DSD Regulations are viewed by some as controversial because they seek to regulate an athlete’s physiology. As outlined above, Semenya contends that her testosterone levels are ‘natural’, whereas the IAAF argues that ‘natural’ advantages such as height should be treated differently from the advantage in certain female events that testosterone at above 5 nmol/L offers. 

It could be argued that this unfortunate wording will not help the IAAF’s case, but it does outline the argument at the heart of the issue. On one side is the view that the testosterone levels of DSD athletes offer them an unnatural and unfair advantage in the Restricted Events. On the other side is the view that such advantages are not unfair, and are as natural as differences in height, lung capacity and other physiological variables. It will be interesting to see if the CAS is able to find the middle ground.

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