The law requires publicly held companies that are incorporated in California to have at least one woman on their boards by the end of 2019, becoming the first state with a female board requirement. By 2021, they’ll have to have two to three women, depending on the size of the board.

Hannah-Beth Jackson, a Democratic state senator who helped write the law, said a quarter of publicly traded companies in California don’t have women on their boards. According to a report by PwC, only a quarter of S&P 500 companies have more than two women on their boards.

The law is likely to face legal challenges. In order for a gender preference of this kind to be upheld, the state must show that governmental action is the best way to achieve the outcome, and that there’s a governmental reason for pursuing it. For Governor Brown, who will leave office in early 2019, signing the law the weekend after Brett Kavanaugh was voted out of committee was more likely a symbolic rejection of gender-based discrimination than a good faith effort to enact a law.

In a letter to the California State Senate that was copied to the Senate Judiciary Committee, Governor Brown explained his reasoning for signing the bill despite potential legal challenges: “Recent events in Washington, D.C. — and beyond — make it crystal clear that many are not getting the message.”