Allison B. Rumsey

Allison Rumsey is Co-Chair of the firm’s Environmental Practice Group. Her practice centers on environmental litigation and enforcement, including state and federal regulatory actions, class actions, citizen suits and business disputes. She represented BP in litigation arising from the Deepwater Horizon oil spill brought by the United States, citizen and environmental groups, states and foreign states.

Allison also assists and defends clients addressing environmental permitting laws in large infrastructure and other projects. Her work has involved the development of a gold mine, construction of a railroad bridge across a major waterway and redevelopment of a large sports field on federal land. Alongside her litigation practice, she advises clients on federal and state regulatory compliance programs. Her experience includes matters involving CERCLA, RCRA, the Clean Air Act, the Clean Water Act and the National Environmental Policy Act.

Before joining the firm, Allison served in the U.S. Department of Justice’s Environment and Natural Resources Division as Counsel to the Assistant Attorney General. She also handled several high-profile environmental cases as an Honors Trial Attorney in the division’s Natural Resources Section and received the Distinguished Service Award. Allison has worked extensively on environmental issues in South Africa and teaches Environmental Law as an Adjunct Professor at Georgetown University Law Center.

Allison clerked for the Honorable Harold Greene of the U.S. District Court for the District of Columbia and the Honorable Harry T. Edwards of the U.S. Court of Appeals for the District of Columbia Circuit.

• Chemours, as lead counsel, on enforcement litigation brought by the State of North Carolina, relating to the discovery of chemicals in the Cape Fear River in North Carolina attributable to the client's facility.
• Chemours, as lead counsel, in eleven toxic tort class action lawsuits brought by homeowners around facility, and public water utilities.
• Ship Owner Liability Insurer of large shipping company in lawsuits resulting from an underwater oil pipeline leak in California.
• Donlin Gold LLC, in permitting challenges brought in Federal Court in Alaska.
• BPXP as part of a team in lawsuits brought by the United States under the Clean Water Act and Oil Pollution Act and other actions claiming violations of a variety of federal and state laws, brought as a result of the oil spill by the state of Louisiana, citizen groups, and environmental groups, among others.

• FORTUNE 100 company in a cost recovery action brought by the United States at Cape Canaveral Air Force Station.
• FORTUNE 500 company in CERCLA litigation related to the cleanup and redevelopment of shorefront property and the remediation of Hudson River sediments.
• Major chemical company in a natural resource damages matter arising from historic contamination of the Ottawa River in Toledo, Ohio.
• Wind developer in permitting of a large wind farm in Wyoming.
• Large oil company as part of a team in negotiations with the U.S. Environmental Protection Agency over alleged Clean Air Act permitting issues at a refinery.
• FORTUNE 100 company in providing legal counseling on the impact of listings under the Endangered Species Act on a wind farm development.
• International pulp and paper company on the implications of the new regulatory landscape climate change on their business.
• FORTUNE 100 company in providing legal assistance both on compliance with federal greenhouse gas regulations, policies, and programs and understanding opportunities created by those new regulations.

• J.D., Georgetown University Law Center, 1992, magna cum laude, Order of the Coif
• B.A., Middlebury College, 1985, cum laude

• District of Columbia
• Colorado

The Legal 500 US “Leading Partners” Environment: Litigation (2025-2026)

“Recommended Lawyer” Product Liability, Mass Tort and Class Action: Toxic Tort — Defense (2026)
“Recommended Lawyers” Energy Regulation: Electric Power (2025)

Lawdragon 500 - Leading Environmental Lawyers – The Green 500 (Environmental Litigation) (2023-2026)

• Adjunct Professor, Environmental Law, Georgetown University Law Center

• Instructor, Environmental Law Institute Superfund and Clean Water Act Bootcamp

• United States Court of Appeals, District of Columbia Circuit, The Honorable Harry T. Edwards
• U.S. District Court, District of Columbia, The Honorable Harold H. Greene

• Honors Trial Attorney, Natural Resources Section, U.S. Department of Justice
• Counsel to the Assistant Attorney General, Environment and Natural Resources Division, U.S. Department of Justice