A Los Angeles County judge declared a controversial housing law that abolished single-family zoning in California unconstitutional, but the state is likely to appeal the narrow ruling.

Passed in 2021, SB 9 allows single-family homeowners to split their lots in two and build two homes on each lot, allowing up to four units on each lot previously zoned for just one.

Five Southern California cities (Redondo Beach, Carson, Torrance and Whittier and Del Mar) sued the state in 2022, claiming the law was unconstitutional because it interfered with their local authority over land use and zoning.

The Los Angeles County Superior Court judge’s ruling, issued Monday, means that SB 9 cannot be applied in these five cities. The judge is expected to issue a ruling next month that could repeal SB 9 statewide.

The attorney general’s office says it is reviewing the decision and “will consider all options in defense of SB 9.”

Housing advocates fear the court ruling will gut a key piece of legislation aimed at increasing density across the state.

“It is already clear that this particular court ruling will nullify the future prosecution of SB 9,” said Rafa Sonnenfeld, policy director for the pro-housing group YIMBY Action.

Chris Elmendor, a law professor at the University of California, Davis, called it “the most ridiculous opinion any court has ever issued in a housing case.”

At the center of the case is the local authority and what gives the state the right to interfere. In California, the Constitution requires state laws preventing local control of cities to demonstrate a reasonable relationship between the stated intent of the legislature and the design of the law.

In the case of SB 9, that stated intent was to improve housing affordability.

The dominant theory in housing policy in recent years is that the state’s decades-long lack of housing supply has driven up the cost of renting and homeownership, and that building more housing (both market-rate and subsidized) will improve affordability. That was reflected in the design of SB 9, which allows more homes to be built by dividing lots. In contrast to state-subsidized affordable housing or deed restrictions that limit rent, the affordable housing created by SB 9 would be what housing policymakers call “naturally occurring.”

But Judge Curtis Kin ruled that the legislature’s intent — housing affordability — did not match the design. Because SB 9 does not require that any units constructed be actually below market rate, it was not “reasonably related to or sufficiently adapted” to ensure access to affordable housing and was therefore unconstitutional.

The judge’s opinion echoed critics’ doubts that increasing supply actually increases affordability.

“The decision confirms that most so-called housing affordability laws are a sham and will not result in much-needed affordable housing,” said Susan Candell, a Lafayette City Council member and proponent of the Our Neighborhood Voices initiative, which seeks return local land use decisions to cities.

“In Redondo Beach we support laws that reasonably address the affordable housing crisis, but this is not one of them,” said City Attorney Michael Webb. “This would simply create more market-rate housing.”

The opinion is a victory for CalCities, a group that lobbies on behalf of the state’s cities, which filed an amicus brief arguing that SB 9 has stripped cities of their discretion to determine the location, density and characteristics of the housing site without guaranteeing construction. of more affordable housing units.

“The court’s ruling reaffirms the fundamental principle that land use planning and zoning are local matters,” League of California Cities Executive Director and CEO Carolyn Coleman wrote in a statement.

But housing advocates say the judge’s ruling is based on a narrow definition of housing affordability.