An attorney Levi drafted a trust document that lists him and Reuven as co-trustees for Shimon
Shimon claims that there was an irregularity (or even a forgery) in the execution of the trust which Levi and Reuven deny.
Shimon sued Levi in secular court without a heter bais din or even a attempt to issue an hazmana.
At the same time Shimon wants to take Reuven to Beis Din. May Reuven refuse? Would a beis din even hear a case where a related party has been called to secular court?
Batei din — at least ones that I know — will not be prepared to accept the case, unless Shimon will first withdraw the case from court, and bring both cases before beis din.
The halachah is that “ein nizkakim,” meaning we do not accept a case of somebody who has brought a case to court.
The Tumim (26:4) writes that this applies only after the decision in court is given. However, others understand that the very fact that a person is involved in court procedures is enough to refuse the person’s entry to beis din (see Biur Ha-Gra 26:4).
One way or the other, when a litigant comes to beis din, beis din will not accept his case unless he agrees to close his case in court. A person is not permitted to try his hand in both.
Although in this case Shimon has separated between Reuven and Levi, this is an artificial separation, because the case against them is the same. Therefore, it stands to reason that beis din will not accept the case unless Shimon closes his case in court.