An interruption in the continuity of possession in both the Roman and common law meanings of the term can be of great practical and legal consequence. This chapter concerns voluntary and involuntary losses of possession. In the Roman tradition, involuntary dispossession generally leaves the former possessor in an altered and disadvantageous legal position relative to the current possessor (see Cases 56–59), although the ownership interest itself remains unimpaired. At common law, an involuntary dispossession, called an “ouster,” is tantamount to the assertion of a would-be owner’s common law right to exclude others from his or her property. Wrongful ousters, if uncontested, will initiate the running of the statutory limitations period for bringing an action of “ejectment” (for real property) or “replevin” (for personalty) to recover the property. Only the putative owner of the property interest to which the right of possession is incident (or the owner’s agent or guardian, etc.) has standing to bring such actions, whereas in Roman law the wrongfully dispossessed party, regardless of the ownership interest, has the remedy of an “interdict” for recovery of the possession (see the Excursus following Case 55 in the Casebook). While ousters at common law can ultimately lead to the acquisition of property by adverse possession or prescription, in Roman law only a lawful possession can lead to prescription or usucapion, and lawful possession can only be founded on a “just cause” (iusta causa). In both legal traditions, a voluntary surrender of possession will terminate the accrual of any prescriptive rights.