When Bruce Wagman of Schiff Hardin told management at one of his first law jobs that he wanted to do pro bono work in the area of animal law, the firm told him that wasn’t an option. So Wagman left.

Flash forward more than a decade, and animal law has become one of the fastest-growing areas of study in the U.S., with nearly 100 courses available to law school students (just nine schools offered such courses in 2000) and more high-profile litigation than ever.