I am looking for a translation for the Hebrew term משפט זוטא (literally, "small trial").
This term denotes a procedure in which a defendant in a trial, after having confessed in earlier interrogation, claims during the trial that the confession was obtained by illegitimate means and should not be used as evidence. When this happens, the "main" trial is paused and the court turns to discuss the validity of the confession; in this "trial within a trial" the original defendant now has to prove his claim, while the original prosecution defends its position that the confession is valid.
This procedure is supposed to originate from the English (British) legal system. The literal translation Minitrial seems to be an American term and has a completely different meaning. I am not sure there is an equivalent procedure in the American judicial system.
I am looking for an answer from British English speakers. Does this procedure exist, and is there a name for or?