California, United States of America
The following excerpt is from People v. Adams, 19 Cal.App.4th 412, 23 Cal.Rptr.2d 512 (Cal. App. 1993):
However, even if a witness violates an exclusion order by attendance at the trial, the violation does not mean that a defendant has been denied a fair trial. The violation also "does not render the witness incompetent to testify, and does not furnish grounds to refuse permission to testify, at least where the party who seeks to offer the testimony was not 'at fault' in causing the witness's violation of the exclusion order. [Citations.]" (People v. Redondo (1988) 203 Cal.App.3d 647, 654, 250 Cal.Rptr. 46.)
Similarly, this statute authorizing an exception from exclusion for witness-support persons during the prosecuting witness's testimony contains adequate safeguards for the prevention of collusive testimony. (People v. Redondo, supra, 203 Cal.App.3d at p. 654, 250 Cal.Rptr. 46.) Consequently, the provision of section 868.5 which allows a support person-witness to sit in the audience does not affect the presumption of innocence by bringing impermissible factors into play.