Reuven receives permission from bais din to seek damages in secular court from m’saraiv Shimon.
Suppose Reuven is awarded a) more money than bais din would have awarded, b) money for vandalism damages committed by Shimon’s 11-year old son, c) grama damage caused by Shimon, and/or d)compensation for “psychological suffering” caused by Shimon (i.e. a category of damage that bais din would not consider).
Does halacha require Reuven to give back the money that was awarded only because Shimon refused to go to Bais Din?
Although the permission from beis din allows you to take the person to court, the permission is restricted to obtaining, via the secular courts, the sum that you are owed according to Torah law. Beyond this sum, Reuven has to return the money to Shimon. However, it is permitted for him to keep the legal expenses incurred in taking Shimon to court.
In addition, if there is a claim from which Shimon is exempt because of gerama, or concerning which there is a safek, it might be permitted to keep the money given by court, depending on circumstances. Under certain circumstances, the money ruled by the court might be considered a form of tefisah.
Sources: [Concerning money ruled by courts above the sum granted by Torah law] See Haflaah, Choshen Mishpat 26:4; Chiddushei Rabbi Akiva Eiger 26:1; Chasam Sofer, Choshen Mishpat 23; this also emerges from Shulchan Aruch 28:2-3.