Environmental law
From 1986 until 2017, Kennedy was a senior attorney for the Natural Resources Defense Council (NRDC), a non-profit environmental organization. From 1984 until 2017, he was a board member and attorney for Hudson Riverkeeper. Earlier in his legal career, he served as assistant district attorney in New York City. For over thirty years, Kennedy has been an adjunct professor of Environmental law at Pace University School of Law. Until August 2017, he also held the post as supervising attorney and co-director of Pace Law School's Environmental Litigation Clinic, which he founded in 1987. He is currently professor emeritus at Pace.