Kernrechtsfrage
Whether the tenant's late submission should be admitted in view of the social investigative principle and cantonal procedural rules.
Extrahierter Entscheid
The late submission was inadmissible under cantonal law; Art. 274d OR did not override the requirements of Art. 164 ZPO/SG.
Extrahierte Begründung
The federal tenancy investigative principle does not eliminate cantonal limits on new submissions in appeal proceedings. The tenant failed to show timely grounds for admissibility.