Dismissal of appeal against arbitral award for violation of right to be heard and principle of equal treatment denied

Facts

Parties and procedural participants:

The appellants are claimant 1 (a lawyer) and claimant 2 (his law firm, a Swiss partnership). The respondents are defendant 1 (a Liechtenstein establishment) and defendant 2 (a Liechtenstein trustee company), who together act as trustees of several Liechtenstein trusts (including the [E.] Trust, [F.] Trust, [G.] Trust). The [J.] Trust was originally also a trustee but later withdrew.

Facts of the case:

Claimant 1 was a long-standing advisor and confidant of the late [H.H.] , a wealthy private individual who established a complex trust structure. Following [H.H.] ’s death in 2015, disputes arose among the beneficiaries, particularly between the daughters [L.] and [M.] , the latter allegedly attempting to unlawfully enrich herself from the estate. Claimant 1 was appointed executor of the English estate and was to be compensated for his services. The respondents are alleged to have inadequately compensated him and his law firm for services related to the estate.

On 14 and 28 January 2022, the parties concluded a procedural agreement providing that disputes could be resolved either before a state court or an arbitral tribunal under the Swiss Rules seated in Zurich with German as the procedural language. The arbitral tribunal was to consist of a sole arbitrator.

Arbitration proceedings:

On 31 January 2025, claimants 1 and 2 initiated arbitration proceedings with the Swiss Arbitration Centre (SAC). Dr. [N.] was appointed as sole arbitrator. In their statement of claim dated 20 June 2025, the claimants filed seven applications seeking payment of several hundred thousand Swiss francs and pounds sterling in total, as well as a declaration of liability claims against the trusts. On 6 November 2025, the sole arbitrator issued a final arbitral award in which he granted only part of the first application (CHF 43,454.25) and dismissed all other applications.

Appeal to the Federal Supreme Court:

On 20 November 2025, the appellants filed an appeal in civil matters with the Federal Supreme Court, seeking the annulment of the final arbitral award—except for the partial granting of the first application and the dismissal of the seventh application—and a remittal of the matter to the sole arbitrator for a new assessment. They alleged, in particular, a violation of the right to be heard, a breach of the principle of equal treatment, and a violation of public policy. They also claimed a ground for revision on the basis of a new fact, as they had only gained access to a mandate agreement dated 23 May 2016 after the arbitral award was issued.

Considerations

Admissibility of the appeal:

The Federal Supreme Court reviews appeals in civil matters against international arbitral awards under Arts. 190–192 PILA. An appeal is admissible only on the grounds exhaustively listed in Art. 190(2) PILA. The appellants must precisely substantiate these objections and may not confine themselves to merely appellatory criticism of the arbitral award. Moreover, the appeal is purely quashing in nature; the Federal Supreme Court may only annul the arbitral award, not decide the matter itself, unless it concerns the jurisdiction of the arbitral tribunal or the composition of the tribunal. The Federal Supreme Court bases its judgment on the facts as established by the arbitral tribunal and reviews only whether one of the grounds for appeal listed in Art. 190(2) PILA is present.

Objection based on a ground for revision:

The appellants argued that they had only obtained the mandate agreement dated 23 May 2016 after the arbitral award was issued, which substantiates their fee claims. They claimed this agreement constituted a ground for revision under Art. 190a(1)(a) PILA. The Federal Supreme Court dismissed this objection, as the appellants did not explain why they could not have submitted the agreement during the arbitration proceedings. Moreover, they did not sufficiently substantiate their argument but merely asserted in general terms that they had obtained the agreement «without fault» only later. In doing so, they failed to meet the heightened substantiation requirements for an appeal in arbitration law.

Objections alleging violation of the right to be heard, the principle of equal treatment, and public policy:

The appellants alleged that the arbitral tribunal had violated their right to be heard by making findings of fact that had not…