Cal. Military and Veterans Code § 162

The Governor, as Commander in Chief, shall appoint the Adjutant General, who shall be on state active duty, in the grade of lieutenant general, with the advice and consent of the Senate, and that person shall hold office at the pleasure of the Governor, or until their successor is appointed and has qualified. A person is not eligible for appointment as Adjutant General unless they have no less than a total of 10 years of commissioned service in the National Guard of the United States, of which at least four years shall be service as a field grade officer in the California National Guard within the preceding 10-year period prior to the date of appointment and of which at least four years shall have been in command of army or air troops at the battalion or equivalent or higher command level or four years as a staff officer at brigade or equivalent or higher staff level.