He was the son of Ed Nevin Jr., a San Francisco born Irish Catholic and his wife, Mazie McDermott.
He joined the San Francisco Police Department in 1965, serving for 27 years and reaching the rank of Inspector[4] Nevin was named Daly City planning commissioner in 1979.
[6] From 1992, when he retired from the SFPD, until 2004 (when he was term-limited out) he served on the San Mateo County Board of Supervisors, advocating the medicinal use of marijuana during his tenure.
[5][2][7] Nevin was the first proposer of a plan to legalize the distribution of medical marijuana in San Mateo County through government-run facilities, which became law in 1997.
[9] In his political career, Nevin focused on transportation issues, including the expansion of BART and Caltrain, as well as gun control, education, and health care.