California Code, Code of Civil Procedure - CCP § 2034.420

The deposition of any expert described in subdivision (b) of Section 2034.210 shall be taken at a place that is within 75 miles of the courthouse where the action is pending.  On motion for a protective order by the party designating an expert witness, and on a showing of exceptional hardship, the court may order that the deposition be taken at a more distant place from the courthouse.