With a post-trial challenge to grand jury proceedings, appellant is entitled to a remedy only if he can establish that the irregularity resulted in prejudice. This case resulted from an automatic appeal from a death penalty sentence. The case was initiated by indictment rather than complaint. The court did not swear in the grand jury until midway through the proceedings. At that time, the prosecutor had presented his opening statement, the detective testified, and part of a recording of appellant’s confession was played. After the indictment was returned, appellant moved to set it aside pursuant to Penal Code section 995, but the trial court denied the motion. Appellant then filed a petition for writ of mandate and the appellate court denied it without comment. Following his conviction, on appeal, appellant contended that the failure to swear in the grand jury constituted fundamental jurisdictional error and he was entitled to reversal. The court disagreed, observing that the appellant failed to establish prejudice. The need for a showing of prejudice depends on the stage of the proceedings in which defendant raises the issue in the reviewing court, and with a post-trial challenge to grand jury proceedings, any irregularity requires reversal only if prejudice is shown. The fact that appellant filed the 995 motion pretrial does not change this requirement. In the current proceeding, appellant is not entitled to relief because he cannot establish prejudice. Substantial evidence was presented after the swearing-in to support the indictment.