Since 2001, Professor Westmoreland has taught at Georgetown about health law, about federal budgets, and about legislation. Prior to that, he was the senior policy fellow at the Federal Legislation Clinic. 

He has worked extensively on public health and health finance policy. He has served as Counsel to the Subcommittee on Health and the Environment in the U.S. House of Representatives and later as the Director of the Medicaid program at HHS. Outside of government, he served as counsel to the Advisory Committee on Tobacco Policy and Public Health and as an advisor to both the Henry J. Kaiser Family Foundation and the Elizabeth Glaser Pediatric AIDS Foundation. He has been the recipient of a Robert Wood Johnson Foundation Investigator in Health Policy Award, working on budget process and health policy.