SAN FRANCISCO — “It will fill up, I promise.” Erin Smith, executive director for the Family Violence Appellate Project, sounded worried about the small crowd at the third annual “legal” battle of the bands. It was still early at 1015 Folsom, a venue that has housed electronic and hip-hop juggernauts, but Smith was hoping to raise a lot of money for her nonprofit, which represents abuse victims in court.

Up on stage later in the evening would be bands from O’Melveny & Myers, Latham & Watkins, Lieff Cabraser Heimann & Bernstein, Kirkland & Ellis, Jones Day and Google Inc.’s legal department. Audience members would vote with their dollars—whichever band raised the most money took home the crown. All proceeds would go to the Family Violence Appellate Project. The venue came free.