Validity of Rent Arrears Notice and Lease Termination

The court addressed the validity of a notice to pay rent arrears, which served as the basis for a subsequent termination of two leases, finding that the notice under Art. 257 OR is lawful if the amount due is clearly determinable, such as by specifying the unpaid month and referencing the parties' established payment practice, even without an explicit Swiss Franc amount. The court reasoned that despite arguments regarding representation, procedural details, and alleged set-offs, the landlord's demand sufficiently clarified the arrears for the months of November 2004 and October 2005, totaling CHF 4,000, based on the consistent monthly rent payments previously made by the tenant, thereby upholding the validity of the termination and ordering the tenant's eviction.