Cal. Public Utilities Code § 1353

(a) The commission may make and file its written findings of fact upon matters concerning which evidence has been introduced before it which, in its judgment, have bearing on the value of the property of the public utility affected. These findings shall be subject to review by the courts in the same manner and within the same time as other orders and decisions of the commission. (b) The findings of the commission so made and filed, when certified under the seal of the commission, shall be admissible in evidence in any action, proceeding, or hearing before the commission or any court in which the commission, the state, or any officer, department, or institution thereof, or any county, city and county, city, or other body politic and the public utility affected may be interested, whether arising under this part, or otherwise. These findings, when so introduced, shall be conclusive evidence of the facts therein stated as of the date therein stated under conditions then existing, and these facts may only be controverted by showing a subsequent change in conditions bearing upon the facts therein determined.