Before entering federal service, Goffman was a senior attorney at Environmental Defense (formerly known as the Environmental Defense Fund) focusing on air pollution problems. He has previous experience in the U.S. Senate Committee on Environment and Public Works as the Democratic chief counsel (1989-1990) but is most known for his work at the Office of Air and Radiation (OAR) from 2009 to 2017 as the Associate Assistant Administrator for Climate and Senior Counsel where “he provided policy and legal counsel on a wide range of climate policy and Clean Air Act regulatory and implementation issues and rulemakings.” From late 2017 to when he rejoined the EPA in January 2021, Goffman was Executive Director of the Environmental & Energy Law Program at Harvard Law School.