Cal. Health & Safety Code § 17031.5

(a) No person operating employee housing shall terminate or modify a tenancy by increasing rent, decreasing services, threatening to bring or bringing an action to evict, refusing to renew a tenancy, or in any other way intimidating, threatening, restraining, coercing, blacklisting, or discharging an employee or tenant because of the tenant’s exercise of any of the following acts:
1. (1) Complaining in good faith, orally or in writing, to the operator, landlord, or employer about tenantability or about any right provided by this part.
2. (2) Exercising any legal right with respect to the housing provided by this part.
3. (3) Complaining in good faith, orally or in writing, to any applicable enforcement agency about tenantability or about any right provided by this part.
4. (4) Bringing an action to enforce any rights provided for by this part or Chapter 2 (commencing with Section 1940) of Title 5 of Part 4 of Division 3 of the Civil Code.
5. (5) Bringing an action under Section 1942.5 of the Civil Code.
(b) The tenant shall have a defense of retaliation in any action for possession if the employer or landlord acted in violation of this section. If the employer or landlord acts to discharge an employee or tenant or to modify or terminate a tenancy within six months after the employee or tenant has exercised any of the acts enumerated in subdivision (a), there is a rebuttable presumption affecting the burden of proof that the employer’s or landlord’s action was retaliatory.
(c) No tenant shall have a defense of retaliation in an action for possession where tenantability is an issue of fact and the untenantable condition was caused by the deliberate or negligent act or omission of the tenant or a member of his or her family, or other persons on the premises with his or her consent.