A: Is a ruling in beis din subject to appeal?
A: The Gemara (Sanhedrin 88b) describes a hierarchy of batei din when the local beis din is divided or in doubt how to rule. However, there was no formal appeals court for a ruling that was already issued. Nonetheless, if an error is found in the ruling or if new information comes to light, the ruling of beis din can be revoked by the initial beis din or by one of greater authority (C.M. 25:1-3).
On a routine basis, one beis din need not check up after another beis din. However, in intricate matters, nowadays since not all batei din are fully qualified, there is halachic basis for a more qualified beis din to review the decision of another beis din. Many others disagree and permit review only if the first beis din issued its decision pending approval of a greater beis din. Practically speaking, in absence of a beis din hierarchy, the decision of a beis din is final (see C.M. 19:2; Pischei Teshuvah 19:3; Yabia Omer C.M. 2:2; Mishpetei Uziel C.M. 4:1).