Peter E. Seley is co-chair of Gibson, Dunn & Crutcher's Environmental Litigation & Mass Torts Practice Group.  Mr. Seley has represented clients handling foreign and domestic environmental matters for more than 20 years, and has been at the forefront of developing jurisprudence in mass tort litigation, expert testimony, and the use of U.S. discovery mechanisms in foreign litigation.

Mr. Seley is a Vice Chair of the ABA SEER Committee on Environmental Litigation and Toxic Torts and was recognized in the National Law Journal's first edition of Energy & Environmental Trailblazers as one of the leading legal innovators on energy and environmental issues.  In 2014, The National Law Journal named Gibson Dunn the Washington, D.C. Litigation Department of the Year for Mass Torts, and Law360 named Gibson Dunn one of its Environmental Practice Groups of the Year for 2014.

One of Mr. Seley's recent cases, featured in multiple articles in legal trade publications and on 60 Minutes, involves a fraudulently obtained $19 billion judgment against Chevron for alleged environmental damages associated with oil production in the Oriente region of Ecuador.  Mr. Seley led a team of Gibson Dunn attorneys in bringing more than 20 discovery actions in jurisdictions around the United States. Information developed during that discovery revealed that the Ecuadorian judgment was the product of fraud, and as a result, Chevron filed a civil RICO action in the Southern District of New York against the plaintiffs' lawyers and co-conspirators involved in the Ecuador case and filed an international arbitration action against Ecuador. 

Mr. Seley was one of the leaders of the Gibson Dunn trial team for the seven-week RICO trial in late 2013.  In early 2014, the Southern District of New York issued a 487-page opinion finding that the plaintiffs' lawyers and their co-conspirators had violated the RICO Act and conspired to violate the RICO Act, committing acts of extortion, mail and wire fraud, money laundering, obstruction of justice and witness tampering. That ruling was upheld by the Second Circuit in 2016 and the U.S. Supreme Court in 2017.

Mr. Seley has managed a number of significant internal investigations regarding environmental issues, including investigations regarding greenhouse gas emissions and climate change, compliance with regulatory requirements for automobile emissions, management of oil field wastes, and compliance with environmental regulations during wind-up of resource extraction operations.  A number of these investigations are cross-border, multinational investigations involving billions of dollars of potential expenditures and the risk of civil or criminal sanctions.  

Mr. Seley regularly handles mass tort and "contaminated community" toxic tort cases in courts around the country. He has, for example, handled cases involving personal injury and property damage claims based on vapor intrusion and exposure to crude oil in soil, allegations of exposure to hexavalent chromium and TCE in air and groundwater, and claims based on releases of solvents and metals from an aircraft manufacturing facility.

Mr. Seley also has represented clients and industry coalitions impacted by state and federal agency action, including a multi-circuit challenge to an EPA Clean Water Act rulemaking impacting the nation's pulp and paper industry, an APA challenge to a Department of Interior rulemaking on an agricultural payment-in-kind program, a challenge to the Department of the Interior's "Roadless Rule" that would have made more than 50 million acres of woodlands off-limits for active management, Clean Air Act challenges to California regulation of automobile emissions and Virginia's adoption of California "Zero Emission Vehicles," and a variety of NEPA challenges to the Department of the Interior's efforts to take agricultural land for various projects in South Florida.

Mr. Seley has defended clients in numerous citizen suits and State and Federal enforcement actions, involving a variety of different statutory and regulatory programs, including a multi-million dollar citizen suit in the Maryland District and Bankruptcy Courts alleging violations of the Clean Air Act, Clean Water Act, TSCA, and various state laws, a multi-million dollar citizen suit in Southern Florida alleging violations of the Endangered Species Act and Clean Water Act, a $600 million Clean Air Act/New Source Review EPA enforcement action in Maryland, a large CERCLA/RCRA groundwater cleanup action in Southern California, a multi-million dollar  CERCLA claim in Pennsylvania federal court involving novel successor liability issues, a multi-site Clean Water Act /RCRA criminal enforcement action in Virginia, and pre-enforcement defense of several clients investigated or in receipt of Notices of Violation under the Clean Air Act, Clean Water Act,  RCRA, and State analogues.

Mr. Seley has represented clients prosecuting and defending CERCLA cost-recovery and contribution actions, including defending a $500 million CERCLA cost recovery action in Southern California, defending a multi-million dollar CERCLA claim in Virginia involving novel mixed funding/orphan share issues, prosecuting a $250 million CERCLA action against the United States for contribution based on government involvement at a contractor-operated manufacturing facility in California, and prosecuting a $100 million CERCLA action against the United States for involvement at a WWII-era aircraft component facility in New York.

Mr. Seley's work also includes significant matters before Federal appellate courts, including appeals in the Second, Third, Fourth, Fifth, Sixth, Ninth, Tenth, Eleventh, and D.C. Circuits, and amicus briefs filed in numerous appellate courts and in the Supreme Court.


  • Cornell University - 1993 - Juris Doctor
  • Princeton University - 1990 - Bachelor of Arts


  • District of Columbia Bar