daf bit: Bava Batra 34

Two men were arguing over the ownership of a riverboat, each claiming to own it. One went to the beit din (court) and said: attach (that is, impound) the boat until I can bring my witnesses. Should the court do so? Rav Chuna says yes, and Rav Yehudah says no. The beit din attached the boat and the man was not able to find his witnesses; he then asked them to release the boat (so the two men could fight over it). Should they release? Rav Yehudah says no; Rav Papa says yes. The halacha follows Rav Yehudah: the court should not attach in the first place, but if it did so it should not then release it. (34b)

The reasoning, explained in a note in the Soncino edition, is that once the court has possession, it should only release to the rightful owner (and we don't know who that is). I'm not sure why it's not ok for the court to restore things to their prior status, but that appears to be the law.