Barry Breen is a Principal Deputy Assistant Administrator at the U.S. EPA. Previously, he was Publications Director at the Environmental Law Institute, a trial attorney at the U.S. Department of Justice, and an Army Captain in the Army's Office of General Counsel.

Mr. Breen was managing editor of Sustainable Environmental Law, which won the annual Best New Book award from the Association of American Publishers in the legal scholarly category. He wrote eight of the annual competition problems for the National Environmental Moot Court. In 2019, he was named the Environment, Energy, and Resources Government Attorney of the Year, by the American Bar Association's section of environment, energy, and resources.

Mr. Breen graduated from Princeton University and Harvard Law School.