As per Article 1428, When, after an action to enforce a civil obligation has failed the defendant voluntarily performs the obligation, he cannot demand the return of what he has delivered or the payment of the value of the service he has rendered. For example, A debtor, who has failed to pay his obligation, is sued by the creditor and instead of losing the case, he has won it. The debtor voluntarily performs his obligations, he cannot demand the return of what he has delivered or payment of the value of the service he has rendered.