SAN MATEO (CBS SF) – Attorney General Xavier Becerra’s office announced Tuesday that it will intervene in a battle over a proposed condo complex on the Peninsula, in a case that poses a challenge to state law aimed at increasing affordable housing.

Becerra’s office is joining an appeal (.pdf) brought on by housing advocacy groups that sued the City of San Mateo for rejecting a 10-unit condominium complex in a residential area. Advocates argued the decision violated the Housing Accountability Act, a decades-old state law limiting when multi-unit housing proposals that comply with building codes can be rejected.

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In November, a judge sided with the city, saying that the Housing Accountability Act does not apply to San Mateo since it is a charter city. The housing advocates filed their appeal late last week.

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“We all have to work together to take on this challenge and that starts with having the units we need to meet demand. This is about upholding our state’s laws and doing our part to ensure that all Californians have a place to live,” Becerra said in a statement.

“I have asked the Attorney General to intervene in this case to defend the validity of this important tool and its application throughout the state, including to charter cities,” Gov. Gavin Newsom said. “California will defend our ability to tackle the cost crisis by holding all cities accountable to statewide housing policy.”

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The Attorney General’s office cited figures by the state’s Department of Housing and Community Development, saying that 180,000 new homes need to be built to keep up with demand, but housing production in the last decade has averaged less than 80,000 new homes a year.

Becerra’s office said more than half of the state’s population live in charter cities.

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According to the League of California Cities, 121 of the state’s cities are charter cities, allowing for greater authority over local affairs. The Bay Area’s three largest cities of San Francisco, Oakland and San Jose are charter cities, along with some smaller communities such as Albany and Piedmont.