In 20 years as a San Francisco plaintiffs lawyer, Lori Andrus has secured top roles in mass tort cases against companies including Farmers Group, Bayer and Johnson & Johnson over pay discrimination, defective birth control and other ills.

She wants more women to join her.

Backed by research highlighting a persistent gender imbalance in mass torts, Andrus and others are encouraging more women to step forward — and more judges to appoint them to leadership roles.