Q: In what situations is a person granted permission to litigate in civil court?
A: When the defendant refuses the summons of beis din, some write that beis din will grant permission to sue in civil court only when there is indication that he is liable. However, the general practice nowadays is to grant permission even when beis din does not know whether he is liable (see Nesivos and Aruch Hashulchan 26:2; Erech Shai 26:2).
When a person is sued in civil court without permission of beis din, he should have the plaintiff summoned by beis din to adjudicate there. Otherwise, it would be construed as accepting the civil court as a binding authority. Meanwhile, the defendant is permitted to respond and defend himself against the claim in civil court to prevent loss. (See Rema C.M. 22:2, 388:5; Maharsham 1:89.)