California Code, Evidence Code - EVID § 731

(b) In any county in which the superior court so provides, the compensation fixed under Section 730 for medical experts appointed for the court's needs in civil actions shall be a charge against the court. In any county in which the board of supervisors so provides, the compensation fixed under Section 730 for medical experts appointed in civil actions, for purposes other than the court's needs, shall be a charge against and paid out of the treasury of that county on order of the court.

(c) Except as otherwise provided in this section, in all civil actions, the compensation fixed under Section 730 shall, in the first instance, be apportioned and charged to the several parties in a proportion as the court may determine and may thereafter be taxed and allowed in like manner as other costs.