A state judge has declared unconstitutional a landmark California law requiring women to serve on company boards.

Superior Court Judge Maureen Duffy-Lewis ruled that the 2018 bill violated the state constitution's equal protection clause. The rule mandated publicly traded firms located in California to have up to three female directors by 2021, depending on the size of the board.

The law was challenged by the conservative legal group Judicial Watch, which claimed that using taxpayer dollars to enforce a law enforcing a gender-based quota violated the California Constitution's equal protection guarantee. Judge Duffy-Lewis concurred in her 28-page decision, saying that "the plaintiff's evidence is compelling."

"The court eviscerated California's unconstitutional gender quota mandate," Judicial Watch President Tom Fitton said in a statement. The California Secretary of State's Office didn't immediately respond to a request for comment.

Back then, Gov. Jerry Brown signed the bill into law in September 2018, noting that it might be overturned, but stating that he wanted to send a statement in the #MeToo era.

"Given all the special privileges that corporations have enjoyed for so long, it's high time corporate boards include the people who constitute more than half the 'persons' in America," Brown wrote in announcing his signing of the bill.

The law was doomed from the start, with a legislative analysis warning that it would be impossible to defend, and then-Gov. Jerry Brown stated that he was signing it despite the possibility that it would be overturned by a court. Brown stated that he signed the legislation to send a statement during the #MeToo era.

It has been credited with raising the status of women on business boards in the three years it has been in effect.

The state defended the law as constitutional, claiming that it was necessary to overcome a culture of discrimination that benefited men and that it was enacted only after other measures had failed. The state further claimed that the statute did not constitute a quota because boards may add seats for female directors without displacing men.

The law was passed while the tech industry grappled with concerns about diversity. Women in technology were in short supply. In 2018, Equilar, a board recruitment firm, discovered that 20.4% of Russell 3000 Index technology businesses have no women on their boards.

According to the California Partners Project, a law sponsor, women currently account for 26.5% of public firm board members after the law was adopted in 2018.