In 2002, Nadia Costa, then a second-year land use associate at Bingham McCutchen, drove two hours to the women’s prison in Chowchilla, Calif., for what she thought would be a simple and quick pro bono project.

Inside, she met Deborah Peagler, a pretty, polite woman in heavy denim pants who leaned over a crowded cafeteria table and told her story.