Question juridique clé
Whether the employer sufficiently substantiated a mistake under Art. 63 OR for set-off and counterclaim
Solution extraite
No. The employer failed to plead with sufficient specificity the alleged error about the debt obligation and the circumstances of the payment.
Motifs extraits
Under the investigative rule in Art. 343 para. 4 OR, parties still must substantiate their allegations. As the employer was represented by counsel and had been expressly alerted by the employee, the court was not required to prompt further substantiation.