Cal. Civ. Code § 6

  § 6. Investigations; records; reports. 1. The commission is authorized
to make such studies and investigations, to conduct such hearings, and
to obtain such information as the commission deems necessary or proper
in prescribing any regulation or order under this act or in the
administration and enforcement of this act and regulations and orders
thereunder.
  2. The commission is further authorized, by regulation or order, to
require any person who rents or offers for rent or acts as broker or
agent for the rental of any housing accommodations to furnish any such
information under oath or affirmation, or otherwise, to make and keep
records and other documents, and to make reports, and the commission may
require any such person to permit the inspection and copying of records
and other documents and the inspection of housing accommodations. The
administrator or any officer or agent designated by the commission for
such purposes, may administer oaths and affirmations and may, whenever
necessary, by subpoena require any such person to appear and testify or
to appear and produce documents, or both, at any designated place.
  3. For the purpose of obtaining any information under subdivision one,
the commission may by subpoena require any other person to appear and
testify or to appear and produce documents, or both, at any designated
place.
  4. The production of a person's documents at any place other than his
place of business shall not be required under this section in any case
in which, prior to the return date specified in the subpoena issued with
respect thereto, such person either has furnished the commission with a
copy of such documents certified by such person under oath to be a true
and correct copy, or has entered into a stipulation with the commission
as to the information contained in such documents.
  5. In case of contumacy by, or refusal to obey a subpoena served upon,
any person referred to in subdivision three, the supreme court in or for
any judicial district in which such person is found or resides or
transacts business, upon application by the commission, shall have
jurisdiction to issue an order requiring such person to appear and give
testimony or to appear and produce documents, or both; and any failure
to obey such order of the court may be punished by such court as a
contempt thereof. The provisions of this subdivision shall also apply to
any person referred to in subdivision two, and shall be in addition to
the provisions of subdivision one of section ten.
  6. Witnesses subpoenaed under this section shall be paid the same fees
and mileage as are paid witnesses under article eighty of the civil
practice law and rules.
  7. Upon any such investigation or hearing, the commissioner or an
officer duly designated by the commission to conduct such investigation
or hearing, may confer immunity in accordance with the provisions of
section 50.20 of the criminal procedure law.
  8. The commission shall not publish or disclose any information
obtained under this act that the commission deems confidential or with
reference to which a request for confidential treatment is made by the
person furnishing such information, unless the commission determines
that the withholding thereof is contrary to the public interest.
  9. Any person subpoenaed under this section shall have the right to
make a record of his testimony and to be represented by counsel.