California Code, Penal Code - PEN § 1203.044

(a)(1) In instances where a defendant is charged with a controlled substance offense and granted probation, the court shall order a drug treatment program or drug education pursuant to Section 11373 of the Health and Safety Code if an appropriate program with capacity to accept the defendant has been identified by the probation officer.

(2) If, at any point during the probation period, evidence is presented that the defendant is not in compliance with the treatment program or education, the court may revoke probation and, upon a determination that the defendant has willfully failed to comply with the treatment program or education, impose a new grant of probation pursuant to subdivision (e) of Section 1203.2.

(3) When referring a person pursuant to this subdivision, the court shall determine the person's ability to pay.  If the court finds that the person is financially unable to pay, the court shall develop a sliding fee schedule for the program based on the person's ability to pay.  A person who meets the criteria set forth in Section 68632 of the Government Code shall not be responsible for any costs.