California Code, Penal Code - PEN § 2657

(a) No person confined in a state prison, as defined in Section 4504, shall be subject to any institutional disciplinary action subsequent to an acquittal in a court of law upon criminal charges brought and tried for the act or omission which is the sole basis of the institutional disciplinary action.

(b) Where the act or omission resulting in acquittal is in any way referred to in any Department of Corrections file pertaining to the prisoner, the fact of acquittal by a court of law shall be clearly inscribed near each such reference.