Questione giuridica chiave
Whether refusing third-party joinder under Art. 83 CPC/VD was arbitrary.
Decisione estratta
Yes. The refusal was unsustainable because Art. 83 CPC/VD expressly allows joinder for a recourse claim, and the court gave no case-specific reason showing excessive procedural complication.
Motivazione estratta
The cantonal court misread solidarity rules and the later federal solidarity-differentiation concept as excluding joinder. The Federal Court held that these substantive rules do not control procedure. The recourse claim gives a direct interest, and the record showed no excessive complication from joining a single co-obligor.