Cal. Bus. & Prof. Code § 2570.18

(a) A person shall not represent to the public by title, education, or background, or by description of services, methods, or procedures, or otherwise, that the person is authorized to practice occupational therapy in this state, unless authorized to practice occupational therapy under this chapter.
(b) Unless licensed to practice as an occupational therapist under this chapter, a person may not use the professional abbreviations “O.T.,” “O.T./L.,” or “O.T.D.,” “Occupational Therapist,” “Occupational Therapist Licensed,” “Occupational Therapist Doctorate,” or any other words, letters, or symbols with the intent to represent that the person practices or is authorized to practice occupational therapy.
(c) A licensee who has earned a doctoral degree in occupational therapy (OTD) or, after adoption of the regulations described in subdivision (e), a doctoral degree in a related area of practice or study may do the following:
1. (1) In a written communication, use the initials OTD, DrPH, PhD, or EdD, as applicable, following the licensee’s name.
2. (2) In a written communication, use the title “Doctor” or the abbreviation “Dr.” preceding the licensee’s name, if the licensee’s name is immediately followed by an unabbreviated specification of the applicable doctoral degree held by the licensee.
3. (3) In a spoken communication while engaged in the practice of occupational therapy, use the title “Doctor” preceding the licensee’s name, if the licensee specifies that he or she is an occupational therapy practitioner.
(d) A doctoral degree described in subdivision (c) shall be granted by an institution and program accredited by the Western Association of Schools and Colleges, the Accreditation Council on Occupational Therapy Education, or by an accrediting agency recognized by the National Commission on Accrediting or the United States Department of Education that the board determines is equivalent to the Western Association of Schools and Colleges.
(e) The board shall define, by regulation, the doctoral degrees that are in a related area of practice or study for purposes of subdivision (c).
(f) Unless licensed to assist in the practice of occupational therapy as an occupational therapy assistant under this chapter, a person may not use the professional abbreviations “O.T.A.,” “O.T.A/L.,” or “Occupational Therapy Assistant,” “Licensed Occupational Therapy Assistant,” or any other words, letters, or symbols, with the intent to represent that the person assists in, or is authorized to assist in, the practice of occupational therapy as an occupational therapy assistant.
(g) The unauthorized practice or representation as an occupational therapist or as an occupational therapy assistant constitutes an unfair business practice under Section 17200 and false and misleading advertising under Section 17500.
(h) An occupational therapist that is serving as an educator in an education program for occupational therapists in California must be licensed. The licensure requirement also applies to an occupational therapist that is serving as an educator in an education program for occupational therapy assistants in California.
(i) An occupational therapy assistant that is serving as an educator in an education program for occupational therapy assistants in California must be licensed.