What is the legal test for a witness exclusion order?

Pursuant to Evidence Code section 777, a trial court may exclude any witness from the courtroom who is not at that time under examination so that witness does not hear the testimony of other witnesses. The purpose of a witness exclusion order is to prevent tailored testimony and aid in the detection of testimony that is less than candid. (People v. Valdez (1986) 177 Cal.App.3d 680, 687.) The remedy for violation of the exclusion order is usually contempt rather than disqualification of a witness. (Id. at p. 692.) Where fault is shared by counsel or the party in violating the order, a court can order the disqualification of a witness. Only where there is no fault by counsel or a witness, is contempt the sole sanction. (Id. at pp. 695-696.)