In a recently published decision, the Supreme Court refused to set aside an arbitral award issued by the Court of Arbitration for Sport (CAS) despite its finding that the applicant's right to be heard had been violated. The Supreme Court considered that this violation had not affected the outcome of the case and thus did not justify the setting aside of the award.(1)


The case pertained to the suspension of a professional tennis player and the disqualification of her results following her violation of anti-doping rules. Arguing a violation of her right to be heard in relation to the start date of her suspension, she challenged the CAS's award, which had increased her suspension from two to 10 months, starting from the issuance of the award, minus the two-month suspension already suffered.


The Supreme Court first questioned whether the player still had an actual interest in the admission of the challenge, considering that she had not challenged the principle of the suspension nor the duration thereof and had already incurred a large part of the 10-month suspension by the time the Supreme Court had issued its decision. However, the Supreme Court left this question open because the challenge was unfounded for other reasons.(2)

The Supreme Court then recalled that the right to be heard is a constitutional guarantee of a formal nature, but that its violation is insufficient to annul the challenged decision if it is unclear that such a violation had an impact on the outcome of the case.(3) Therefore, a party relying on a violation of its right to be heard must establish that the arbitral tribunal ignored allegations, arguments or evidence that were likely to have affected the outcome of the case.(4)

Against this background, the Supreme Court considered that the CAS had violated the player's right to be heard by assessing her interests and results after the hearing in relation to the possibility of starting the suspension even before the CAS's decision ordering such suspension (so-called 'backdating'),(5) without questioning the parties.

However, while the player could have argued (had she been questioned) that her results had been globally negative in the months following the hearing and that backdating the suspension would have been less harmful for her, she could not have predicted her future results and prizes and thus the effect of backdating. Further, under the applicable rules, backdating is discretionary and constitutes an exception. Therefore, the Supreme Court found that the player had not established that the violation of her right to be heard had affected the outcome of the case and thus dismissed the challenge.(6)


The formal nature of the right to be heard has long been recognised by the Supreme Court. Applied strictly, it entails that an award affected by such a violation must be set aside, irrespective of whether the violation affected the outcome of the case.(7) However, the Supreme Court's more recent practice tends to depart from a strict application of the formal nature of the right to be heard and to require the applicant to establish a causal link between the asserted violation and the (adverse) outcome of the case.(8) The decision commented herein seems to confirm this tendency.

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(1) Supreme Court, 4A_424/2018, 29 January 2018 (in French).

(2) Ground 3.

(3) Ground 5.2.2.

(4) Ground 5.2.2.

(5) Ground 5.7. The CAS had found that:

[t]he Athlete who was not provisionally suspended and no longer ineligible to compete was free to compete as of 3 October 2017, and won prizes and advanced in the ranking which would have been disqualified for the period of backdating. Compared to those losses which are certain, it is uncertain how successful the Athlete may be in any future tournaments. (Ground 5.3.)

(6) Ground 5.7.

(7) DTF 121 III 331, Ground 3.c.

(8) Supreme Court, 4A_247/2017, 18 April 2018, Ground 5.1.3.