California Code, Business and Professions Code - BPC § 4996.15

(a) Nothing in this article shall restrict or prevent psychosocial activities by employees of accredited academic institutions, public schools, government agencies, or nonprofit institutions who train graduate students pursuing a master's degree in social work in an accredited college or university.  Any psychosocial activities by the employee shall be part of a supervised course of study and the graduate students shall be designated by titles such as social work interns, social work trainees, or other titles clearly indicating the training status appropriate to their level of training.  The term “social work intern,” however, shall be reserved for persons enrolled in a master's or doctoral training program in social work in an accredited school or department of social work.

(b) Notwithstanding subdivision (a), a graduate student shall not perform clinical social work in a private practice or a professional corporation.