21. Estoppel and jus tertii.

At common law1, a carrier (in common with any other bailee) is estopped from denying his bailor's title; he may not, in response to his bailor's2 demand for a redelivery of the goods, plead the superior right or title of a third person to the property in those goods3. The estoppel ceases to bind the carrier, however, when the bailment on which it is founded is determined by conduct constituting an eviction of the carrier by title paramount4. The carrier is thereby discharged from all liability to his bailor, unless there is a special contract or the carrier is