Kernrechtsfrage
Whether the tenant's extraordinary termination of the lease for just cause under Art. 266g(1) CO was valid.
Extrahierter Entscheid
Yes. The landlords' conduct, viewed as an accumulation of retaliatory acts after the tenant asserted his rights, made continued performance objectively intolerable.
Extrahierte Begründung
Just cause requires exceptionally serious, unforeseeable circumstances not attributable to the terminating party. The cantonal court could reasonably find that the landlords' repeated actions, taken together, crossed that threshold; the Federal Court found no misuse of discretion.