Suretyship Validity and Contractual Interpretation

The court addressed the proper classification of a security agreement where a party co-signed both a lease and a subsequent loan agreement as a "Solidarhafterin," leading to a debt collection action after the principal debtor defaulted on the loan. The court reasoned that based on a normative interpretation of the contract texts, which evidenced a linked intention to secure multiple financial obligations, the key element was the explicitly agreed-upon subsidiary nature of the co-signer's liability—only taking responsibility after the primary debtor was unsuccessfully pursued, leading to the qualification of the agreement as a simple suretyship (Bürgschaft). However, the court ultimately upheld the lower court's finding that the suretyship was void due to the failure to specify a maximum amount for the secured obligation as required by the statutory form provisions for suretyship contracts.