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Stacey Halliday’s practice draws on her diverse litigation and regulatory experience in advising clients on issues pertaining to environmental justice, compliance, enforcement, and corporate social responsibility issues. With particular experience in the energy and technology sectors, she has helped lead critical environmental audits, investigations, and enforcement matters.

Stacey represents electronics and textile industry clients in product regulatory compliance and global supply chain issues, including electronic-right-to-repair and product-labeling requirements. She also advises on energy transition and climate change matters, contaminated sites, as well as highly technical sustainability disclosures.

As a senior member of the Environmental Protection Agency’s oversight response team, Stacey provided legal and strategic guidance on congressional investigation and hearing preparation. She played a key role in the EPA’s incident response and crisis management of the Flint drinking water crisis, the Gold King Mine spill, and the legal defense of the Clean Power Plan and Clean Water Rule. While serving as Special Counsel in the EPA’s Office of General Counsel, Stacey coordinated the agency’s response to the U.S. Commission on Civil Rights investigation of the EPA’s Title VI program.

Before joining Arnold & Porter, Stacey was a principal at a Chambers-ranked law firm, where she led the Environmental Justice practice.


  • Leading national energy utility in designing and implementing programs to incorporate environmental justice considerations in project decision-making.
  • A large municipality in a Title VI investigation by the EPA and the U.S. Department of Transportation. 
  • Industry-focused guidance and a 50-state survey on environmental justice legislation and resources.
  • Corporate environmental due diligence, including environmental compliance programs, environmental audits, and environmental management systems.
  • Corporate social responsibility, including strategies and program development related to sustainability, circular economy implementation, and environmental justice.
  • Mandatory environmental disclosures, voluntary nonfinancial reporting, and green marketing in accordance with domestic reporting requirements and global standards.
  • Federal environmental enforcement in connection with federal investigations and overseeing compliance measures in court-appointed monitorships.
  • Regulatory compliance for utilities and municipalities involving the Clean Water Act, the Safe Drinking Water Act, the National Environmental Policy Act, and Title VI of the Civil Rights Act of 1965.


Beyond the Bottle: Insights on the Consumers Journey Towards Sustainable Products
American Cleaning Institute
What’s Behind the Rise in ESG Challenges?
Panelist, American Bar Association Antitrust Law Spring Meeting
Purchaser’s Participation in Environmental Diligence — Securing BFPP Defenses Against CERCLA Liability
Halliday Shares Thoughts on Recent Louisiana Civil Rights Ruling
Inside EPA
Arnold & Porter’s Environmental Group Welcomes Stacey Halliday
Environmental Edge: Climate Change & Regulatory Insights


The Legal 500 US
"Next Generation Partner" Environment: Regulatory (2023-2024)
Chambers USA
"Up and Coming" Environment (Washington, D.C.) (2024)
“Rising Star” (2022)



  • J.D., Howard University School of Law, 2011
  • A.B., Political Science and French, Harvard University, 2005


  • District of Columbia
  • New York

Government & Military Service

  • Special Counsel, Immediate Office, Office of General Counsel, U.S. Environmental Protection Agency (2015-2017)
  • Law Clerk, Fraud and Public Corruption, U.S. Attorney’s Office, Washington, D.C. (2010-2011)
  • Law Clerk, Federal Major Crimes, U.S. Attorney’s Office, Washington, D.C. (2010)


  • District of Columbia Court of Appeals, The Honorable Anna Blackburne-Rigby


  • Member of Board and Leadership Council, Environmental Law Institute (2020-present)
  • Board Member, D.C. Safe (2018-2021)
  • Vice Chair, Board, National Environmental Justice Conference (2021-present)
  • Member, Environmental Justice Advisory Board, Multistate, Environmental Response Trust, Greenfield Environmental Trust Group (2021-present)
  • Member of Council, Section on Environment, Energy and Resources, American Bar Association (2022-present)
  • Special Advisor, Environmental Justice Task Force, American Bar Association (2022-present)
  • Vice Chair for Environmental Justice/Just Transition, Climate Change Committee, American Bar Association (2021-present)
  • Chair, Membership Diversity Enhancement Program, American Bar Association (2019-2022)


  • French