California Code, Penal Code - PEN § 2981

For the purpose of proving the fact that a prisoner has received 90 days or more of treatment within the year prior to the prisoner's parole or release, the records or copies of records of any state penitentiary, county jail, federal penitentiary, or state hospital in which that person has been confined, when the records or copies thereof have been certified by the official custodian of those records, may be admitted as evidence.