The trial court's order taxing the defendant’s claim for expert witness fees included in its cost bill is vacated and remanded, where: 1) a voluntary dismissal constitutes the conclusion of the action and is therefore an appropriate precipitating event triggering the trial court's discretion as to the assessment of expert witness fees under California Code of Civil Procedure section 998; and 2) the trial court erred to the extent it required the defendant, who had made a valid section 998 offer, to first obtain a judgment in the case before the trial court would consider its claim for recovery of expert witness fees.