Corporate lawyers can’t often use their specialized skills for work that fits the classic definition of pro bono. But Drinker Biddle & Reath corporate partner William Clark Jr. has set out to change the nature of the corporation itself in a way that benefits society. Clark, based in Philadelphia, has been the legal and legislative muscle behind the nationwide effort to write state laws allowing the establishment of benefit corporations, or entities that are chartered not only to seek profit but to provide social and environmental benefits.

The idea, promoted by Clark’s pro bono client B Lab, is a sort of hybrid between a nonprofit and a corporation. Traditional corporations that spend capital on projects such as saving the rain forest or fighting hunger risk suits from shareholders who would prefer the money returned to them as dividends. Nonprofits can receive tax exemptions but are supposed to spend revenues on projects that further their mission.