Activision Blizzard Inc., which has faced allegations of sexual harassment, and Monster Beverage Corp. are among the companies that have a month to add women to their boards to comply with a California law promoting gender diversity.

Unless a judge finds the rule itself is a form of discrimination.

A trial is due to start Wednesday in Los Angeles over whether the law can be enforced. It’s likely to take at least seven days. The case was brought by the conservative advocacy group Judicial Watch, which claims the law is unconstitutional because it violates the Equal Protection Clause of the California Constitution.