Federal Rules of Civil Procedure, Rule 42(b)
Separate Trials. For convenience, to avoid prejudice, or to expedite and economize, the court may order a separate trial of one or more separate issues, claims, crossclaims, counterclaims, or third-party claims. When ordering a separate trial, the court must preserve any federal right to a jury trial.
California Code of Civil Procedure § 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.
Trickey v. Superior Court, 252 Cal. App. 2d 650, 653 (1967)
[The objective of bifurcation] is avoidance of the waste of time and money caused by the unnecessary trial of damage questions in cases where the liability issue is resolved against the plaintiff.
Cohn v. Bugas, 42 Cal. App. 3d 381, 385-86 (1974) (citations omitted)
Section 598 of the Code of Civil Procedure gives the trial court power to order “that the trial of the issue of liability shall precede the trial of any other issue in the case, except for special defenses which may be tried first pursuant to Section 597” on motion of a party in a jury case, and on its own motion in a nonjury case. “Its objective is avoidance of the waste of time and money caused by the unnecessary trial of damage questions in cases where the liability issue is resolved against the plaintiff.
The court, however, over the objection of a party, cannot order the separate trial of an issue of liability when because of the nature of the case it is necessary to prove the plaintiff’s damages in order to establish that liability. In Cook v. Superior Court (1971) 19 Cal. App.3d 832 [97 Cal. Rptr. 189], the plaintiff sought to recover damages from his former attorney for negligent prosecution of a claim for damages for medical malpractice. The trial court, on motion of the attorney, ordered that the issues relating to the alleged medical malpractice be tried first. On application of the plaintiff a writ of prohibition was issued by the Court of Appeal. It ruled, “In an action by a client against his attorney to establish liability for malpractice in the prosecution of a case, the client must show the attorney was negligent in prosecuting the case and, but for such negligence, the case would have resulted in the recovery and collection of a judgment favorable to the client. Thus the issue of liability includes not only a showing the attorney was negligent but also a showing his negligence caused damage. Factors of damage essential to proof of the issue of liability against the attorney would also be factors essential to proof on the issue of damages. Thus, where trial of the question of liability is bifurcated by requiring a trial of the issues of legal malpractice the court, in substance, is directing a trial of some of the issues on the question of damage before a trial on some of the issues on the question of liability. The authority of the court to bifurcate a trial of the issues in a case is conferred and limited by the provisions of Code of Civil Procedure section 598. The statute does not authorize the court to order the trial of a part of the issue of liability and a part of the issue of damages before the trial of another part of the issue of liability…. An act which exceeds the defined statutory power of a court is in excess of its jurisdiction and may be restrained by a writ of prohibition.”