What is the legal basis for establishing the validity of a claim and obligating the defendant to the demand, when the defendant acknowledges the authenticity of the submitted documents?

The court relies on the defendant's acknowledgment of the authenticity of the submitted documents to establish the validity of the claim and obligate the defendant to the demand. A private instrument is considered proof against its signatory unless explicitly denied, in accordance with Article 29 of the Law of Evidence. Furthermore, the court may infer what it deems appropriate from the documents if the litigant fails to respond, in accordance with Article 21 of the same Law.