Cal. Civ. Code § 120

  § 120. Use of dwelling units in a class A multiple dwelling for other
than permanent residence purposes. 1. Notwithstanding any other
provision of law to the contrary, within a class A multiple dwelling to
which this article is applicable the use of dwelling units as a hotel
for other than permanent residence purposes, as defined in paragraph a
of subdivision eight of section four of this chapter, that would
otherwise be prohibited shall be permitted to continue for a period of
two years after the effective date of this section provided that:
  a. such dwelling units were used for other than permanent residence
purposes on January first, two thousand nine and on the effective date
of this subdivision and fifty-one percent or more of the total number of
dwelling units in such dwelling were used for other than permanent
residence purposes on such dates;
  b. (1) such dwelling was initially constructed as and identified on
its initial certificate of occupancy as "apartment hotel" or "class A
hotel" and occupied as a hotel for other than permanent residence
purposes on December fifteenth, nineteen hundred sixty-one or, if such
dwelling was under construction and not yet complete on such date, was
occupied as a hotel for other than permanent residence purposes at the
time the dwelling was completed, or (2) such dwelling is in zoning
district C5 as designated in the New York city zoning resolution and was
initially constructed as a hotel for other than permanent residence
purposes prior to December fifteenth, nineteen hundred sixty-one and
occupied as a hotel for other than permanent residence purposes on
December fifteenth, nineteen hundred sixty-one, or (3) such dwelling (A)
is within twelve hundred feet of zoning district C5 as designated in the
New York city zoning resolution, (B) was initially constructed as a
hotel for other than permanent residence purposes in accordance with a
permit that was issued prior to December fifteenth, nineteen hundred
sixty-one, and (C) was completed after December fifteenth, nineteen
hundred sixty-one and was initially occupied as a hotel for other than
permanent residence purposes;
  c. such dwelling is of fireproof construction and was of fireproof
construction on January first, two thousand nine;
  d. such dwelling units used for other than permanent residence
purposes have at least two lawful means of egress, including exit
stairs, fire towers or exterior stairs but excluding fire escapes and
had such lawful means of egress on January first, two thousand nine;
  e. such dwelling has operational exist signs and a fire alarm system
complying with the provisions for existing transient occupancies in
accordance with local law and had such exit signs and fire alarm system
on January first, two thousand nine; and
  f. such dwelling units used for other than permanent residence
purposes are registered with the department within one hundred eighty
days after the effective date of this section in a form and manner to be
provided by such department, including a requirement that the applicant
submit certification of compliance with paragraphs d and e of this
subdivision, signed and sealed by a registered architect or licensed
professional engineer in good standing under the education law. The
department may assess fees to cover all costs associated with such
registration. The department may refuse to register dwelling units or
may revoke such registration if it determines such dwelling units or
dwelling do not comply with the conditions for registration set forth in
paragraphs a through e of this subdivision.
  2. The owner shall obtain a certificate of occupancy for the use of
registered dwelling units for other than permanent residence purposes
within two years after the effective date of this section. Upon
application prior to the expiration of such two year period, the
department may, for good cause, extend such time for up to one
additional year but no such extension shall be granted unless the
department finds that:
  a. the owner has obtained the necessary permit or permits for all work
necessary to bring such dwelling into compliance with the requirements
of this chapter and all local housing, building and fire codes for the
use of dwelling units for other than permanent residence purposes;
  b. all construction authorized by such permit or permits has been
substantially completed; and
  c. there are no considerations of public safety, health and welfare
that have become apparent since the issuance of the above described
permit or permits that indicate an overriding benefit to the public in
enforcing the requirement that the applicant obtain a certificate of
occupancy for the use of registered dwelling units for other than
permanent residence purposes within two years after the effective date
of this section.
  3. Upon application prior to the expiration of the time for obtaining
a certificate of occupancy, as extended by the department pursuant to
subdivision two of this section, the board of standards and appeals may
grant a further extension of time to obtain a certificate of occupancy
in a case where there are circumstances beyond the applicant's control
or hardship in the way of obtaining such certificate within the time
allowed by the department but no more than one such extension of fifteen
months shall be granted for a building and no such extension shall be
granted unless the board finds that there are no outstanding building or
fire code violations of record at the property.
  4. The department shall issue such certificate of occupancy upon proof
that said dwelling conforms in all respects to the requirements of this
chapter and all local housing, building and fire codes for the use of
dwelling units for other than permanent residence purposes. If no such
certificate of occupancy is issued within two years after the effective
date of this section or, if applicable, within the time as extended by
the department or as further extended by the board of standards and
appeals, all use of dwelling units for other than permanent residence
purposes shall thereafter cease.
  5. If after a certificate of occupancy is issued pursuant to
subdivision four of this section, the use of such dwelling units for
other than permanent residence purposes is discontinued, nothing in this
section shall be construed to limit the application of the local zoning
resolution with respect to such discontinuance.