California Code, Code of Civil Procedure - CCP § 581c

(a) Only after, and not before, the plaintiff has completed his or her opening statement, or after the presentation of his or her evidence in a trial by jury, the defendant, without waiving his or her right to offer evidence in the event the motion is not granted, may move for a judgment of nonsuit.

(b) If it appears that the evidence presented, or to be presented, supports the granting of the motion as to some but not all of the issues involved in the action, the court shall grant the motion as to those issues and the action shall proceed as to the issues remaining. Despite the granting of the motion, no final judgment shall be entered prior to the termination of the action, but the final judgment in the action shall, in addition to any matters determined in the trial, award judgment as determined by the motion herein provided for.

(c) If the motion is granted, unless the court in its order for judgment otherwise specifies, the judgment of nonsuit operates as an adjudication upon the merits.

(d) In actions which arise out of an injury to the person or to property, when a motion for judgment of nonsuit was granted on the basis that the defendant was without fault, no other defendant during trial, over plaintiff's objection, may attempt to attribute fault to or comment on the absence or involvement of the defendant who was granted the motion.