He joined AT&T in 1983 as a telecommunications regulatory attorney, and was an environmental attorney and Senior Environmental Attorney for AT&T from 1984 to 1993. From 1991 to 1992 he was the J. Herbert Holloman Fellow at the National Academy of Engineering in Washington, DC. During 1992, he was the J. Herbert Holloman Fellow at the National Academy of Engineering in Washington, DC. From 1995 to 1997 he was Director for Energy and Environmental Systems at Lawrence Livermore National Laboratory, on temporary assignment from his position as Research Vice President, Technology and Environment, for AT&T. From 1997 to 2004 he was the Environment, Health, and Safety Vice President for AT&T, with global responsibility for those operations for the firm. In 2004, he moved to Arizona State University, where he is now President's Professor, and Lincoln Professor of Engineering and Ethics. In June, 2000, he chaired the second Gordon Conference on Industrial Ecology.