Cal. Civ. Proc. Code § 2032.320

(a) The court shall grant a motion for a physical or mental examination under Section 2032.310 only for good cause shown.
(b) If a party stipulates as provided in subdivision (c), the court shall not order a mental examination of a person for whose personal injuries a recovery is being sought except on a showing of exceptional circumstances.
(c) A stipulation by a party under this subdivision shall include both of the following:
1. (1) A stipulation that no claim is being made for mental and emotional distress over and above that usually associated with the physical injuries claimed.
2. (2) A stipulation that no expert testimony regarding this usual mental and emotional distress will be presented at trial in support of the claim for damages.
(d) An order granting a physical or mental examination shall specify the person or persons who may perform the examination, as well as the time, place, manner, diagnostic tests and procedures, conditions, scope, and nature of the examination.
(e) If the place of the examination is more than 75 miles from the residence of the person to be examined, an order to submit to it shall be entered only if both of the following conditions are satisfied:
1. (1) The court determines that there is good cause for the travel involved.
2. (2) The order is conditioned on the advancement by the moving party of the reasonable expenses and costs to the examinee for travel to the place of examination.