Restitution for Undue Payment Based on Unjust Enrichment

The case concerns a dispute arising from an obligation where a debtor, having made a payment to the creditor, later sought to recover a portion of that payment, arguing it was made under an error or without a valid cause, specifically invoking unjust enrichment principles, which the lower court had rejected. The highest court overturned the lower court's decision, reasoning that the right to recover an undue payment is a general principle of law, independent of specific contractual provisions or detailed proof of error, thereby allowing the claim for restitution based on the absence of a legitimate legal basis for the transferred funds.