Cal. Pen. Code § 5080
The Director of Corrections may transfer persons confined in one state prison institution or facility of the Department of Corrections to another. The Board of Prison Terms may request the Director of Corrections to transfer an inmate who is under its parole-granting jurisdiction if, after review of the case history in the course of routine procedures, such transfer is deemed advisable for the further diagnosis, and treatment of the inmate. The director shall as soon as practicable comply with such request, provided that, if facilities are not available he shall report that fact to the Board of Prison Terms and shall make the transfer as soon as facilities become available; provided further, that if in the opinion of the Director of Corrections such transfer would endanger security he may report that fact to the Board of Prison Terms and refuse to make such transfer.
When transferring an inmate from one state prison, institution, or facility of the Department of Corrections to another, the director may, as necessary or convenient, authorize transportation via a route that lies partly outside this state.
Ca. Pen. Code § 5080