An arbitral award is null and void when it has been rendered in violation of mandatory rules governing the validity of acts of public administration, such nullity resulting in the granting of the challenge pursuant to article 829 of the Code of Civil Procedure and the consequent annulment of the arbitral decision.
The nullity of an arbitral award for violation of mandatory rules of public law may be raised by the court of its own motion even in challenge proceedings, and is not precluded by any attestations or declarations of the public entity which are insufficient to cure the original defect of invalidity affecting the underlying act.
In proceedings to challenge an arbitral award for nullity, once the rescissory phase has been completed with the granting of the challenge, the judge may decide the rescissory judgment directly by applying the principle of the clearest ground (*ragione più liquida*), without the need to remit the case to the arbitral tribunal.