condictio indebitiin Roman law, a personal action to require a defender to make over a sum of money or a thing given to the defender in the belief that the pursuer was legally obliged to give it to the defender when legally the payment was not due; by analogy, a ground for recovery of certain unjust enrichments in Scots law. The remedy is widely known in modern civilian systems and appears in many codifications.
CONDICTIO INDEBITI, civil law. When the plaintiff has paid to the defendant by mistake what he was not bound to pay either in fact or in law, he may recover it back by an action called condictio indebiti. This action does not lie, 1. if the sum was due ex cequitate, or by a natural obligation; 2. if he who made the payment knew that nothing was due, for qui consulto dat quod non debetat, prcesumitur donare. Vide Quasi contract.