The regime governing corporate arbitration, now consolidated in arts. 838-bis and 838-ter cod. proc. civ. by virtue of art. 3, co. 55, d.lgs. n. 149 of 2022 (Cartabia reform), operates exclusively in the field of companies and is founded upon the need to ensure the unitary interest of the corporate group and the uniformity of decisions affecting the corporate relationship. Such special regime — which confers upon the arbitral award binding effect also vis-à-vis members or companies not participating in the proceedings — is not applicable to consortia pursuant to art. 2615 cod. civ., in which the arbitration clause retains a contractual nature and no organisational structure comparable to that of a company exists. It follows that, in matters of consortia, the subjective limits of res judicata under art. 2909 cod. civ. apply, so that the arbitral award is binding only upon the parties to the proceedings and does not produce effects vis-à-vis a consortium member who remained extraneous thereto.
In the matter of the challenge of the arbitral award, in the substitutive phase under art. 830, co. 2, cod. proc. civ. the court of appeal, having annulled the award, decides the dispute on the merits within the limits of the evidentiary material duly available in the proceedings for the challenge, without being able to supplement of its own motion the failure to produce acts and documents from the arbitral proceedings not introduced by the parties, in application of the principle of party disposition over evidence under art. 115 cod. proc. civ. and of the rules on the burden of proof under art. 2697 cod. civ.
The execution by a consortium member of the arbitration clause contained in the consortium's articles does not entail the automatic extension of the effects of the arbitral award rendered in a dispute between the consortium and a third party, in which the consortium member remained extraneous. In matters of consortia, the subjective limits of res judicata under art. 2909 cod. civ. apply, which are also applicable to the arbitral award pursuant to art. 824-bis cod. proc. civ., so that the arbitral award is binding only upon the parties to the proceedings.