In proceedings to challenge an arbitral award, defect of reasoning as a ground of nullity under art. 829 co. 1 n. 5 cod. proc. civ., read with art. 823 co. 2 n. 3, is established only where the reasoning of the award is entirely absent or so deficient that the ratio decidendi cannot be identified, or where the line of argument is so unacceptable as to amount to a non-decision; the ground is not made out where the reasoning, although concise or premised on a partly incorrect legal point, addresses each issue raised in a thorough and detailed manner and properly weighs the evidence.
A challenge to an arbitral award for violation of the rules of substantive law governing the merits of the dispute, under art. 829 co. 3 cod. proc. civ., is admissible not only where expressly agreed by the parties but also where provided for by law; a statutory clause requiring the arbitrators to decide ‘in accordance with law in the form of arbitration (arbitrato rituale), in compliance with the mandatory provisions of the cod. proc. civ. relating to arbitration’ constitutes the reference to ‘law’ within the meaning of art. 829 co. 3 cod. proc. civ. and renders the ground admissible.
A challenge to an arbitral award under art. 829 co. 3 cod. proc. civ. for disregard of substantive rules of law is admissible only within the same limits as an error of law arguable on appeal to the Supreme Court under art. 360 n. 3 cod. proc. civ.; the ground nonetheless fails where the error of law committed by the arbitral tribunal had no adverse bearing on the decision, there being no direct and sufficient causal link between the alleged violation and the ruling, which rests on independent and adequate evidentiary foundations.