Under the law, local governments were allowed the following options: The bill was drafted by Henry J. Mello, who described it as the "Granny housing bill", signed into law by Governor Jerry Brown in January 1983, and came into effect on July 1, 1983.
In 1981, Mello drafted another law, SB 1160, which allowed zoning variances in R1 areas for ADUs and was geared toward seniors.
The law, which was passed by the legislature due to the perception that local governments would not resolve the statewide housing shortage on their own, was the first regulation of ADUs in the state for all ages.
Due to the low-impact approach taken by the legislature at the time, the law did not have much initial effect upon the housing supply, and has been repeatedly amended since to increase housing supply, especially under Governor Gavin Newsom.
[21] The majority of ADUs constructed in California are used for housing, compared to only 8% being used for short-term rentals, according to a survey conducted by the Terner Center for Housing Innovation at University of California, Berkeley.