1Ulpianus, On the Edict, Book LXXVI. Marcellus says that if you sell a tract of land belonging to another, and afterwards, it having become yours, you bring suit against the purchaser for its recovery, you will very properly be barred by this exception. 1The same rule must be held to apply to the owner of the land, if he becomes the heir of the vendor. 2Where anyone sells property of mine under my direction, and I bring an action to recover the same, I will be barred by this exception; unless it is proved that I directed that the property should not be delivered before the purchase-money was paid. 3Celsus says if anyone should dispose of my property for a smaller sum than I directed it should be sold for, it is held not to be alienated, and if I bring suit to recover it, I cannot be barred by this exception, and this is correct. 4If a slave purchases merchandise with money belonging to his peculium, and his master orders him to become free by his will before he obtains the ownership of the property, and bequeaths to him his peculium, and the vendor brings suit to recover the merchandise from the slave; an exception in factum can be pleaded, on the ground that he was a slave at the time he made the contract. 5Where anyone purchases property which was not delivered to him, but of which he obtained possession without fraud, he will be entitled to an exception against the vendor, unless the latter should have good reason for bringing suit to recover the property; for even if he had delivered possession, and he had just cause of action for recovery, he could avail himself of a reply to the exception.

2Pomponius, On Plautius, Book II. If you purchase a tract of land from Titius, which in fact belonged to Sempronius, and after the price was paid he delivers it to you, and Titius then becomes the heir of Sempronius, and sells and delivers the same land to Mævius; Julianus says that it is more equitable, for you have the prior lien, because if Titius himself had attempted to recover the land from you, he would have been barred by an exception; and if Titius himself had held possession of it, you could have recourse to the Publician Action.

3Hermogenianus, Epitomes of Law, Book VI. Ad Dig. 21,3,3 pr.Windscheid: Lehrbuch des Pandektenrechts, 7. Aufl. 1891, Bd. I, § 186, Note 16.The exception on the ground of property sold and delivered is available, not only by him to whom it was delivered, but also by his successors, as well as by a second purchaser, even if it was not delivered to him, for it is to the interest of the first purchaser that the second should not be deprived of the property by eviction. 1On the same principle, the successors of a vendor can be barred, whether they have succeeded to all his rights, or merely to that which has reference to the property involved.