California Code, Penal Code - PEN § 3050

(a) Notwithstanding any other provision of law, any inmate under the custody of the Department of Corrections and Rehabilitation who is not currently serving and has not served a prior indeterminate sentence or a sentence for a violent felony, a serious felony, or a crime that requires him or her to register as a sex offender pursuant to Section 290, who has successfully completed an in prison drug treatment program, upon release from state prison, shall, whenever possible, be entered into a 150-day residential aftercare drug treatment program sanctioned by the department.

(b) As a condition of parole, if the inmate successfully completes 150 days of residential aftercare treatment, as determined by the Department of Corrections and Rehabilitation and the aftercare provider, the parolee shall be discharged from parole supervision at that time.