Art. 47 d.P.R. 1063/1962 (general conditions of contract for public works), in the version prior to the amendment introduced by art. 16 l. 741/1981, confers upon each party to a public works contract the right to exclude arbitral jurisdiction unilaterally, by commencing proceedings before the competent court or by notifying its determination to the other party; such right is in the nature of a potestative right, the exercise of which does not require the consent of the other party.
The reference to the general conditions of contract for public works contained in statutory provisions imposing their mandatory application upon public bodies is in the nature of a normative and ambulatory reference, so that amendments to and supplements of the said conditions apply automatically to the relationships governed thereby, without the need for a separate agreement between the parties.
The appointment of an arbitrator by a party that has previously exercised its right to exclude arbitral jurisdiction pursuant to art. 47 d.P.R. 1063/1962 does not constitute tacit acceptance of arbitral jurisdiction nor a withdrawal of the declination, since the unequivocal character of the act of renunciation cannot be overridden by a subsequent ambiguous course of conduct.
An arbitral award rendered notwithstanding the valid exercise of the right to exclude arbitral jurisdiction pursuant to art. 47 d.P.R. 1063/1962 is vitiated by nullity for want of potestas iudicandi within the meaning of art. 829 co. 1 n. 1 cod. proc. civ.