In its decision 4A_420/2022 of 30 March 2023, the Swiss Federal Tribunal dealt with whether an arbitral tribunal has the power to adjudicate a set-off claim based on a claim outside of the scope of the arbitration clause. The question has been given a positive answer in Swiss domestic arbitration yet it remains controversial in international arbitration. This case stems from the transfer of a football player from a French to an English club. Shortly after the transfer agreement, the player tragically died in an airplane crash. The French club claimed the first installment of the transfer agreement. The English club raised a set-off defense, with a claim in tort based on the alleged liability of the French club in the crash. Both FIFA and the CAS refused to adjudicate the set-off claim. The Swiss Federal Tribunal firstly pointed out that the question of jurisdiction for set-off claim could not be resolved by case law one for all. It then considered that the principle of Swiss law in domestic arbitration could not be transposed to international arbitration. It finally considered that the FIFA had no mandate to allocate set-off claims, so that CAS had rightly denied its jurisdiction on the set-off claim of the English club, and dismissed the appeal.