An application to set aside an award constitutes proceedings of limited review, admissible only where specific grounds are advanced corresponding to the errores in procedendo listed in art. 829, co. 1, cod. proc. civ. or to a breach of the rules of law within the narrow limits permitted, and does not give rise to appellate proceedings authorising a re-examination of the merits of the arbitrators’ decision. The challenge permits only the iudicium rescindens, consisting in the ascertainment of one of the exhaustively listed grounds of nullity, and only once the nullity of the award has been established is a re-examination of the merits possible in the subsequent iudicium rescissorium. A power to manage the dispute conferred on a third party, extending to the assessment of all consequential steps, also includes the challenge to the award, an initiative closely connected with and consequential upon the arbitral decision. The adversarial principle in arbitral proceedings is complied with whenever the parties are given, by whatever means, the opportunity to present their case on all the material in the dispute, in a reasonable manner and within reasonable time, account being taken of the greater flexibility and speed proper to arbitral procedure. Breach of the adversarial principle must be assessed not in formal terms but from the standpoint of an actual impairment of the opportunity to make submissions and to respond, so that the nullity of the award and of the proceedings is to be declared only where the complaint of the defect is accompanied by identification of the specific prejudice caused to the right of defence. A defect in the reasoning renders the award void only where the reasoning is entirely absent or so deficient as not to permit identification of the ratio decidendi, denoting a line of argument dialectically unacceptable which amounts to a non-reasoning, a re-examination of the merits remaining precluded. The defect of ultrapetition arises where the adjudicator rules beyond the limits of the claims and objections advanced by the parties, or on issues extraneous to the subject matter of the proceedings and not capable of being raised of its own motion, granting relief which was not sought or which differs from that claimed; outside such cases, the identification of the true nature of the action and the legal characterisation of the case remain unfettered.