California Code, Government Code - GOV § 65852.1

(a) Notwithstanding Section 65906, any city, including a charter city, county, or city and county may issue a zoning variance, special use permit, or conditional use permit for a dwelling unit to be constructed, or which is attached to or detached from, a primary residence on a parcel zoned for a single-family residence, if the dwelling unit is intended for the sole occupancy of one adult or two adult persons who are 62 years of age or over, and the area of floorspace of the attached dwelling unit does not exceed 30 percent of the existing living area or the area of the floorspace of the detached dwelling unit does not exceed 1,200 square feet.

This section shall not be construed to limit the requirements of Article 2 (commencing with Section 66314) of Chapter 13, or the power of local governments to permit second units.

(b) This section shall become inoperative on January 1, 2007, and shall have no effect thereafter, except that any zoning variance, special use permit, or conditional use permit issued for a dwelling unit before January 1, 2007, pursuant to this section shall remain valid, and a dwelling unit constructed pursuant to such a zoning variance, special use permit, or conditional use permit shall be considered in compliance with all relevant laws, ordinances, rules, and regulations after January 1, 2007.