If the act in which the unlawful or forbidden cause consists does not constitute a criminal offense, the following rules shall be observed:
(1) When the fault is on the part of both contracting parties, neither may recover what he has given by virtue of the contract, or demand the performance of the other's undertaking;
(2) When only one of the contracting parties is at fault, he cannot recover what he has given by reason of the contract, or ask for the fulfillment of what has been promised him. The other, who is not at fault, may demand the return of what he has given without any obligation to comply his promise. (1306)