In certain cases, Italian law requires the joinder of certain parties to the proceedings. For instance, as a general rule, the action aimed at setting aside a contract requires the joinder of all parties thereof.
The topic of such compulsory joinder in arbitration proceedings is partly governed by statutory law (Articles 816-quater and 816-quinquies of the Italian Code of Civil Procedure); nonetheless, its implementation gives rise to several turmoils (as it was noted by a learned author).
What happens if the party whose joinder is required by law is not joined to the proceedings? A possible answer to that question is provided by the Court of Appeal of Campobasso, in its recent ruling (No. 367 of November 7, 2019, Italian text available here).