979. He or she who receives what is not due to him or her, through error of law or of fact, is bound to restore it; or if it cannot be restored in kind, to give the value of it.
If the receiver be in good faith, he or she is not obliged to restore the profits of the thing received.
980. He or she who pays a debt in the erroneous belief that he or she is the debtor, has a right of recovery against the creditor.
Nevertheless that right ceases when the obligation has in good faith been cancelled in consequence of the payment; and the remedy is solely against the true debtor.
981. If the receiver be in bad faith, he or she is bound to restore what has been received, with the interest or profits which should have accrued from the reception or from the beginning of his or her bad faith.
982. If the thing unduly received be a thing certain, the receiver is bound to restore its value, if through his fault or his or her bad faith it have perished or deteriorated, or can no longer be delivered in kind.
If he or she has received the thing in bad faith, or if after having become conscious of error in the reception, he retain it in bad faith, he or she is answerable for its loss or deterioration by accident; unless it would have equally perished or deteriorated in the possession of the owner.
983. If he or she who has unduly received the thing sell it, being in good faith, he or she is bound to restore only the price of sale.
984. He or she to whom the thing is restored, is bound to repay to the possessor, although he or she were in bad faith, the expenses which have been incurred for its preservation.