Grounds for award challenge based on arbitration agreement nullity, lack of arbitrator independence and impartiality, and absence of potestas decidendi are inadmissible under Article 817, paragraph 3, of the Civil Procedure Code when challengers failed to contest such matters in arbitral proceedings and even filed counterclaims.
Award nullity for contradictory provisions under Article 829, paragraph 1, no. 11, of the Civil Procedure Code must be understood as requiring contradictions to emerge between different components of the operative part, not between different parts of reasoning compared with each other or between reasoning and operative provisions.
Internal contradictions in award reasoning may be relevant for nullity purposes only in cases of absolute impossibility to reconstruct the logical and legal reasoning underlying decisions due to total absence of any form of reasoning attributable to its functional legal model.
Complaints of arbitral award nullity for non-observance of legal rules "in iudicando" are admissible only if circumscribed within the same boundaries as law violations opposable through cassation appeals under Article 360, paragraph 1, no. 3, of the Civil Procedure Code, with grounds contesting evaluation of facts and evidence acquired in arbitral proceedings being inadmissible.
Evaluation of facts alleged and evidence acquired during arbitral proceedings is contractually entrusted to arbitrators' institutional competence and cannot be censured in award challenge proceedings.