California has become the first state to require publicly traded companies to include women on their boards of directors.

Gov. Jerry Brown approved the legislation Sunday that forces changes at California-based corporations by 2020. Some European countries already require corporate boards to include women.

A fourth of publicly held corporations with headquarters in California don't have any women on their boards of directors.

State Sen. Hannah-Beth Jackson says having more women on boards will make companies more successful. The Santa Barbara Democrat authored the measure.

The California Chamber of Commerce has argued that the composition of corporate boards should be determined internally, not mandated by government. The chamber says the new law will prioritize gender over other aspects of diversity.

(Copyright 2018 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)

9/30/2018 5:06:00 PM (GMT -4:00)