Under which circumstances can one of the litigants in a din torah claim that the halachic decision / position that the shtar borerut (arbitration agreement) that they signed was so incorrect that the shtar borerut has no validity and they can re-open the din torah?
This is a complex issue, and no comprehensive artument can be given.
The standard shtar borerus is fairly inclusive, giving the dayanim quite extensive jurisdiction over the case, and not leaving much room, excepting a grave error on the part of the dayanim, to open up the case after the verdict is given.
One classic reason, however, for which the case can be re-opened, is if there was no power of attorney to sign the shtar borerus.
For specific cases, please submit a separate question.