When Esther Lardent, a longtime public interest lawyer, founded the Pro Bono Institute in 1996 to encourage law firms to increase their pro bono efforts, she found that firms diverged widely in their commitment to pro bono—and even in how they defined the term. "Pro bono programs tended to be very informal and decentralized," recalls Lardent. "Some were spending 7–8 percent of their time on [legal work for the needy]. Others were raising money for a charity, and that was it."

With their capacity to fund and staff multiple large-scale pro bono projects, large law firms were an undertapped resource that Lardent felt could fundamentally change the pro bono realm. She challenged firms to devote 3–5 percent of their total billable hours to pro bono activities and came up with a standardized definition of pro bono as free legal representation of a charitable, nonprofit, or public interest group. The Pro Bono Institute tracked the hours spent by big-firm lawyers on pro bono, publicizing the firms that spent the most time while advising other firms on how to increase their pro bono efforts.

"Her impact has been unparalleled," says Christopher Herrling, pro bono counsel at Wilmer Cutler Pickering Hale and Dorr. "She, more than any individual I can think of, has brought law firm pro bono into the mainstream and made it so that every major law firm in the U.S. [has established a] pro bono program supported by firm leadership." In 1996, Am Law 200 firms tallied 1.6 million hours of pro bono work. In 2012, it was 4.86 million hours. Meanwhile, Lardent and the institute have expanded the challenge to include in-house legal departments and global pro bono.