California Code, Civil Code - CIV § 1812.524

(a) “Nursing service” means the assignment of a nurse, as a private duty, self-employed, licensed registered nurse, licensed vocational nurse, or practical nurse to render service to a patient under the direction or supervision of a physician or surgeon registered to practice in this state.

(b) “Nurses' registry” means a person who engages in the business of obtaining and filling commitments for nursing service.  A nurses' registry which makes or plans to make referrals for nurses' employment other than private duty nursing shall comply with Chapters 1 (commencing with Section 1812.500) and 2 (commencing with Section 1812.503) of this title with respect to those referrals.

(c) “Private duty nurse” means a self-employed nurse rendering service in the care of either a physically or mentally ill patient under the direction of a physician or surgeon, but who is paid by either the patient or the designated agent of the patient and who accepts the responsibilities of a self-employed private contractor.