Kernrechtsfrage
Whether a time-limited joint suretyship under Art. 510(3) OR expires if the creditor only notifies the surety, without legally asserting the claim within four weeks after expiry.
Extrahierter Entscheid
Yes. For a joint suretyship, the creditor must also legally assert the secured claim within the four-week period; mere notice is insufficient.
Extrahierte Begründung
Art. 510(3) OR applies also to joint sureties and is mandatory. The protective rationale of BGE 125 III 322 for simple sureties does not dispense with legal assertion where no prior enforcement against the principal debtor is required in the same way.