In decision 4A_424/2018, the Swiss Supreme Court rejected an application to set aside a Court of Arbitration for Sport (CAS) award on the basis that, although the award was rendered in violation of the right to be heard, the appellant did not demonstrate that the violation had affected the outcome of the proceedings.

In a French-language decision dated 29 January 2019 but only recently published, despite acknowledging that the appellant's right to be heard had been violated, the Swiss Supreme Court refused to set aside an award issued by the Court of Arbitration for Sport (CAS). Here, there was no evidence showing that the violation had affected the outcome of the proceedings.

In an award issued seven months after the hearing, the CAS Panel ordered the suspension of the appellant, a professional tennis player (the Athlete), from the date of the award. Considering that a retroactive suspension ("backdating") would have disqualified some of the Athlete's results and prizes, including those obtained after the hearing, the Panel decided that a further period of ineligibility was less harmful to the Athlete than backdating.

The Athlete challenged the award before the Swiss Supreme Court, arguing that her right to be heard had been violated regarding the starting point of the suspension, notably because the Panel took into account events that took place after the hearing, without giving the parties an opportunity to address the underlying facts.

By reference to previous case law, the Supreme Court reaffirmed that the right to be heard is infringed where an arbitral tribunal does not consider arguments that are relevant to the award. However, in its appeal to set aside such award, a party must demonstrate that it was prevented from presenting its arguments on an issue that was relevant to the outcome of the proceedings. The Supreme Court confirmed that, where it is unknown whether the violation of the right affected the outcome, the award will not be set aside.

Having recalled these principles, the Supreme Court found that, in assessing the Athlete's interests, as well as her post-hearing results and prizes when considering the backdating issue, the Panel had violated the Athlete's right to be heard. However, the Supreme Court reasoned that backdating is discretionary and that, at the time of the hearing, the Athlete ignored her future results and prizes, and therefore the effect of backdating. Consequently, the Supreme Court concluded that the Athlete had not established that the violation of her right to be heard could have affected the outcome of the proceedings and accordingly dismissed her motion to set aside the award.

Case: Decision 4A_424/2018 (Swiss Supreme Court).