California, United States of America
The following excerpt is from People v. Lamas, F073362 (Cal. App. 2018):
preliminary hearing. (People v. Young (1985) 175 Cal.App.3d 537, 541.)14 Such orders are recognized as a means of " 'discouraging and exposing fabrication, inaccuracy, and collusion.' [Citations.]" (People v. Young, supra, at p. 541.)
"Given that a primary object of preliminary examinations is to ' "weed out groundless or unsupported charges of grave offenses, . . ." ' [citations], witness separation is of more crucial importance at the preliminary examination than at trial. [Citation.] Thus at trial, the court retains discretion to decide whether prior to his testimony a witness should be precluded from hearing the testimony of another witness. [Citations.]" (People v. Young, supra, 175 Cal.App.3d at pp. 541-542; see Evid. Code, 777.)15 The trial court's power in this regard is "broad" (Geders v. United States (1976) 425 U.S. 80, 87), and includes the power to instruct the witnesses not to talk with other witnesses (People v. Hutchings (1908) 8 Cal.App. 550, 555; see 1044).