George Sibley, Hunton Andrews Kurth LLP Photo

George P. Sibley, III



Trey’s practice focuses on environmental permitting and litigation. Trey has served as lead litigation counsel in a diverse array of trials and appeals, including petitions for review of large infrastructure projects, major CERCLA cost-recovery actions, defense of environmental citizen suits and civil enforcement cases, consumer class actions and federal civil rights. Trey combines courtroom experience in complex trials and appeals with the substantive knowledge specific to environmental disputes arising under the federal Clean Air Act, Clean Water Act, National Environmental Policy Act and Endangered Species Act.

Trey was law clerk to the Hon. Karen J. Williams of the US Court of Appeals for the Fourth Circuit from 2003-2004. He also clerked for the Hon. Robert E. Payne of the US District Court, Eastern District of Virginia, from 2002-2003. Before attending law school, Trey served as a Surface Warfare Officer in the United States Navy.


  • Lead litigation counsel for natural gas pipeline company in challenges to project authorizations under the Clean Water Act, Mineral Leasing Act, Endangered Species Act, National Environmental Policy Act, and National Historic Preservation Act (4th Cir. 2017 to present).
  • Lead litigation counsel for pipeline company in challenge to Clean Water Act permit for major oil pipeline (D.D.C. 2020 to present)
  • Appellate counsel for natural gas pipeline company in challenges brought under the Clean Water Act and National Environmental Policy Act to permits necessary for the construction of a major interstate natural gas pipeline. (11th Cir. 2016)
  • Trial and appellate counsel for major phosphate producer in citizen suit challenging federal agencies’ compliance with Clean Water Act, Endangered Species Act, and National Environmental Policy Act in issuing permits under section 404 of the Clean Water Act. (M.D. Fla. and 11th Cir. 2016–2020)
  • Trial counsel for major forest products company in CERCLA cost-recovery action. (W.D. Mich. and 6th Cir. 2011–present)
  • Represented major coal producer in challenge to EPA’s attempt to retroactively veto a Clean Water Action Section 404 permit. (D.C. Cir. and D.D.C. 2010–2016)
  • Briefed and argued issue of first impression in the Third Circuit involving the interstate transport of air pollution. (3d Cir. 2012-2013)
  • Represented major coal producer in putative class action involving claims of private and public nuisance associated with the operation of a coal ash disposal facility; secured complete dismissal of claims (E.D. Okla. 2012-2015)
  • Represented multiple utilities and trade associations in Clean Air Act New Source Review litigation. (2010–present)
  • Represented multiple States in challenge to EPA’s Cross-State Air Pollution Rule. (D.C. Cir. and U.S. S.Ct. 2011–2015)
  • Briefed and argued motion to dismiss for energy producer in Clean Water Act citizen suit involving coal ash landfill. (D.Md. 2010)
  • First-chair trial counsel for Fortune 200 financial institution in complex land-use litigation in Northern Virginia. The case was tried over several days and resulted in complete victory for the client. (Va. Circuit Court, Loudoun County 2007)
  • First-chair trial counsel in civil rights lawsuit brought by a former inmate at a Virginia county jail relating to abuse that occurred while she was incarcerated. The case was tried over two days and resulted in a jury verdict in favor of the client. (W.D. Va. 2008)


Honors & Recognitions

  • Named Best Lawyer in Environmental Law and Litigation - Environmental, The Best Lawyers in America, 2024
  • Named a Litigation Star, Virginia, Benchmark Litigation, 2022-2024
  • Benchmark Litigation – Future Star, 2015-2020



  • Member, American Bar Association
  • Member, Virginia Bar Association
  • Member, John Marshall Inn of Court
  • Member, Fourth Circuit Judicial Conference
  • Member, Federal Bar Association




JD, University of Virginia School of Law, Managing Editor, Virginia Law Review; Order of the Coif, 2002

BA, Political Science, Duke University, cum laude, 1995



District of Columbia


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