Cal. Code Civ. Proc. § 598
The court may, when the convenience of witnesses, the ends of justice, or the economy and efficiency of handling the litigation would be promoted thereby, on motion of a party, after notice and hearing, make an order, no later than the close of pretrial conference in cases in which such pretrial conference is to be held, or, in other cases, no later than 30 days before the trial date, that the trial of any issue or any part thereof shall precede the trial of any other issue or any part thereof in the case, except for special defenses which may be tried first pursuant to Sections 597 and 597.5. The court, on its own motion, may make such an order at any time. Where trial of the issue of liability as to all causes of action precedes the trial of other issues or parts thereof, and the decision of the court, or the verdict of the jury upon such issue so tried is in favor of any party on whom liability is sought to be imposed, judgment in favor of such party shall thereupon be entered and no trial of other issues in the action as against such party shall be had unless such judgment shall be reversed upon appeal or otherwise set aside or vacated.
If the decision of the court, or the verdict of the jury upon the issue of liability so tried shall be against any party on whom liability is sought to be imposed, or if the decision of the court or the verdict of the jury upon any other issue or part thereof so tried does not result in a judgment being entered pursuant to this chapter, then the trial of the other issues or parts thereof shall thereafter be had at such time, and if a jury trial, before the same or another jury, as ordered by the court either upon its own motion or upon the motion of any party, and judgment shall be entered in the same manner and with the same effect as if all the issues in the case had been tried at one time.
Ca. Civ. Proc. Code § 598