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Allison Rumsey's practice focuses primarily on environmental litigation and enforcement matters. Allison represents clients in state and federal regulatory enforcement actions, class actions, citizen suit lawsuits, and business disputes. She represented BP in the litigation brought by the United States, citizen and environmental groups, states, and foreign states arising from the Deepwater Horizon oil spill.

Allison also has an active practice assisting and defending clients in navigating the relevant permitting environmental laws at play in large infrastructure and other projects, including the development of a gold mine, the construction of a railroad bridge across a major waterway, and the redevelopment of a large sports field on federal land.

In addition to litigation, Allison advises clients on federal and State regulatory compliance programs. She has experience in CERCLA, RCRA, the Clean Air Act, the Clean Water Act, and the National Environmental Policy Act, among other statutes.

Prior to joining the firm, Allison was Counsel to the Assistant Attorney General, Environment and Natural Resources Division of the U.S. Department of Justice. As an Honors Trial Attorney in the Natural Resources Section, Allison handled several high-profile environmental cases. She was awarded the Distinguished Service Award.

Allison also has worked extensively in South Africa on a variety of environmental issues. In addition, she is an Adjunct Professor at Georgetown University Law Center teaching Environmental Law.

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


Superfund Liability for PFAS: EPA Designates Two PFAS Chemicals as Hazardous Substances
Environmental Edge: Climate Change & Regulatory Insights
Top Read for 2023: Our Recently Published Clean Water Act Essentials Book
Environmental Edge: Climate Change & Regulatory Insights
Rumsey Quoted in Law360 on Clean Water Act Jurisdiction Rule
Two New Hazardous Substances: The Impact of Listing PFOA and PFOS Under the Comprehensive Environmental Response, Compensation, and Liability Act (pdf)
The Journal of Federal Agency Action, Volume 1, Number 1
Clean Water Act Essentials Third Edition
ABA Book Publishing


Lawdragon Green 500
Leaders in Environmental Law — Environmental Litigation (2023-2024)



  • 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

Government & Military Service

  • 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


  • 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


  • Adjunct Professor, Environmental Law, Georgetown University Law Center

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