Yost served as a CLIPI staff attorney heading its Washington office in the early 1980s.  

Yost is a distinguished environmental law expert with a notable career in both public service and private practice. He served as the first head of the Environmental Section in the California Attorney General’s Office, where he enforced the California Environmental Quality Act (CEQA). Later, he became General Counsel of the U.S. Council on Environmental Quality (CEQ) during the Carter administration, contributing to the development of National Environmental Policy Act (NEPA) regulations.