California Code, Welfare and Institutions Code - WIC § 1800

(a) Whenever the Division of Juvenile Facilities determines that the discharge of a person from the control of the division at the time required by Section 1766, 1769, 1770, or 1771, as applicable, would be physically dangerous to the public because of the person's mental or physical deficiency, disorder, or abnormality that causes the person to have serious difficulty controlling his or her dangerous behavior, the division, through the Director of the Division of Juvenile Justice, shall request the prosecuting attorney to petition the committing court for an order directing that the person remain subject to the control of the division beyond that time. The petition shall be filed at least 90 days before the time of discharge otherwise required. The petition shall be accompanied by a written statement of the facts upon which the division bases its opinion that discharge from control of the division at the time stated would be physically dangerous to the public, but the petition may not be dismissed and an order may not be denied merely because of technical defects in the application.

(b) The prosecuting attorney shall promptly notify the Division of Juvenile Facilities of a decision not to file a petition.