Cal. Civ. Code § 302

  § 302. Certificate of occupancy. 1. No multiple dwelling shall be
occupied in whole or in part until the issuance of a certificate by the
department that said dwelling conforms in all respects to the
requirements of this chapter, except that no such certificate shall be
required for any multiple dwelling existing on July first, nineteen
hundred fifty-two, for which a certificate of occupancy was not required
before such date and in which no changes or alterations commenced on or
after such date have been made except in compliance with this chapter,
and except that a certificate shall be required prior to July first,
nineteen hundred fifty-seven for any dwelling, the plans for the
alteration or conversion of which to multiple dwelling occupancy were on
file with the department or a permit authorizing such conversion was
issued before such date and for which a certificate of occupancy upon
completion of such conversion or alteration was not required before such
date. This exception shall not be deemed to relieve any owner from the
obligation to make such dwelling comply with the applicable provisions
of this chapter.
  2. Except as above provided, no dwelling constructed as or altered or
converted into a multiple dwelling on or after July first, nineteen
hundred fifty-two, shall be occupied in whole or in part until the
issuance of a certificate of occupancy.
  3. The department shall, on request of the owner or of his certified
agent, issue a certificate of occupancy for any old multiple dwelling
not requiring such certificate, provided that, after an inspection by
the department, no violations are found against such dwelling.
  4. A certificate of occupancy shall be issued within ten days after
written application therefor, if the dwelling shall be entitled thereto.
When the department does not issue such certificate within ten days, the
head of the department shall, on the request of the owner or his
certified agent, issue a temporary certificate of occupancy for a
multiple dwelling or a section or a part thereof for a period of ninety
days or less, provided that such certificate shall bear the endorsement
that the dwelling has been inspected by the department and complies with
all the requirements of this chapter, and that such temporary occupancy
will not jeopardize life, health or property. Such temporary certificate
may be renewed at the discretion of the head of the department for
similar periods but shall not extend, together with such renewals,
beyond one year from the date of its original issuance.
  5. A certificate, a record in the department, or a statement signed by
the head of the department that a certificate has been issued, may be
relied upon by every person who in good faith purchases a multiple
dwelling or who in good faith lends money upon the security of a
mortgage covering such a dwelling. Whenever any person has so relied
upon such a certificate, no claim that such dwelling had not, prior to
the issuance of such certificate, conformed in all respects to the
provisions of this chapter shall be made against such person or his
successor in title or ownership with respect to such multiple dwelling
or mortgage, or against the interest of any such person with respect
thereto.
  6. Notwithstanding any general or local law to the contrary, a
certificate issued for any multiple dwelling organized pursuant to the
provisions of article nine-B of the real property law, shall be deemed
issued for each dwelling unit contained within such multiple dwelling in
full compliance with the requirements of this section.