Morgan Lewis

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Related News

04/19/13 Fracking Ruling May Stymie Oil, Gas Projects on U.S. Land, Law360
Environmental Practice partner Ron Tenpas is quoted.
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Morgan Lewis's Appellate Team, led by partner Ted Cruz, was recently named one of the best in the practice of appellate law.
01/22/10 EPA Takes Tougher Approach to Water Quality Management, Environmental Law360
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Photo of  Ronald J. Tenpas

practice accolades


Listed as a Law Firm of the Year for Energy Law by U.S. News and Best Lawyers (2015)

Product Liability & Mass Torts

Named a Class Actions and Mass Torts 'Powerhouse' in BTI's Litigation Outlook 2014 report

honors + affiliations

Listed, Chambers USA: America's Leading Lawyers for Business (2011–2014)

Noted in The US Legal 500 for Environment: Litigation (2014)

Council Member, ABA Section of Public Utility Communications and Transportation (PUCAT); Chair, Environment Committee

Member, Board of Governors, Maryland Federal Bar Association

Member, American Association of Rhodes Scholars

Recipient, Edmund J. Randolph Award for Outstanding Service, U.S. Department of Justice

Recipient, Secretary of the Navy, Distinguished Service Award

bar admissions

  • District of Columbia
  • Maryland
  • Florida
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Ronald J. Tenpas

Washington, D.C.
1111 Pennsylvania Ave., NW
Washington, DC 20004-2541
United States
Phone: +1.202.739.5435
Fax: +1.202.739.3001

Ronald J. Tenpas co-chairs Morgan Lewis's Environmental and Climate Change Practices and is also active in the firm's Appellate, White Collar, Government Relations, and Congressional Investigations Practices.

Mr. Tenpas's practice focuses on matters at the intersection of business activity and government regulation and enforcement. In recent years, he has represented individuals and companies under criminal investigation related to alleged environmental violations, import and customs matters, and false statements to United States agencies. Mr. Tenpas has represented companies responding to Congressional investigations, defending themselves against civil violation notices, and when being inspected for compliance with various environmental regulations. He often represents companies and trade associations in preparing comments related to proposed regulations and in subsequent litigation challenging new regulatory provisions. His practice also includes regularly advising on regulatory compliance questions under the environmental laws, compliance programs, and due diligence issues involved in transactional settings.

Prior to joining Morgan Lewis, Mr. Tenpas served as the Assistant Attorney General (AAG) for the Environment and Natural Resources Division of the U.S. Department of Justice. In that role, he managed a 700-person division that included 400 attorneys, overseeing civil and criminal litigation arising under more than 150 environmental and natural resources laws. In that capacity, he also advised Cabinet and White House officials on policy and litigation risks associated with the environmental laws. The Division's major client agencies included the Environmental Protection Agency and the Departments of Agriculture, Commerce, Defense, Energy, Homeland Security, and Interior. This included litigation in which regulated entities challenge new regulatory commands, and matters in which the government sought to enforce environmental laws due to alleged civil or criminal violations or sought to recover environmental clean-up costs. These matters typically arise under statutes such as the Clean Air Act, the Clean Water Act, CERCLA (Superfund), RCRA, the Pipeline Safety Act, and others. For his service, Mr. Tenpas received the Justice Department's highest honor, the Edmund Randolph Award. His current environmental practice focuses on environmental litigation and counseling under a broad range of environmental statutes.

Prior to serving as AAG, Mr. Tenpas served as an Associate Deputy Attorney General, as the U.S. Attorney in the Southern District of Illinois, and as an Assistant U.S. Attorney in the District of Maryland and the Middle District of Florida. In these positions, Mr. Tenpas personally investigated and tried a variety of white collar matters, including those involving health care fraud and public corruption. He has testified five times before Congress on matters ranging from environmental enforcement to health care fraud to insider trading to identity theft. He chaired the Justice Department's health care fraud coordinating committee, served on the Attorney General's Advisory Committee of United States Attorneys, and served as Executive Director of the seventeen agency Identity Theft Task Force.

Before initially entering private practice and then joining the Justice Department, Mr. Tenpas served as a law clerk to Chief Justice William H. Rehnquist of the U.S. Supreme Court (1991–1992); Judge Louis H. Pollak of the U.S. District Court for the Eastern District of Pennsylvania (1990–1991); and Judge Howard Holtzmann of the Iran-United States Claims Tribunal in The Hague, Netherlands (1992–1993).

Mr. Tenpas received his J.D. from the University of Virginia School of Law in 1990, where he was editor-in-chief of the Virginia Law Review and named to the Order of the Coif. He received a postgraduate B.A. in philosophy, politics, and economics from Oxford University, Balliol College in 1987, where he was a Rhodes Scholar, and his B.A., with high honors, in international relations from Michigan State University in 1985.

Mr. Tenpas is admitted to practice in the District of Columbia, Maryland, and Florida.

Selected Representations

  • Representing a company in responding to a Congressional committee investigation and information request related to hydraulic fracturing practices.
  • Representing a ship's chief engineer in a federal criminal prosecution related to false statements and false record-keeping, securing a highly favorable final resolution of one year's unsupervised probation and a $2,000 fine.
  • Representing a fuel company against the EPA in connection with an alleged failure to secure appropriate renewable fuels trading credits and resolving the matter for a de minimis penalty without concession of liability.
  • Representing a foreign ATV manufacturer in successfully resolving alleged violations related to the import of non-conforming products under the Clean Air Act, including securing conditions allowing the company to resume exports to the U.S.
  • Representing a refinery in a post-incident accident investigation and associated environmental enforcement actions after a refinery fire, including negotiating a favorable non-court settlement with the EPA.
  • Representing an energy company in connection with an internal investigation and in associated consumer product and related disclosure work after the company received indications it had been supplied defective product, successfully avoiding all claims as to potential liability.
  • Counseling a chemical company with respect to clean-up obligations and in negotiations with the EPA at multiple Superfund sites.
  • Representing a chemical company in an administrative law trial before the EPA regarding allegations that the company failed to report alleged adverse risk information.
  • Representing a surgeon excluded from billing in federal health care programs, securing a federal district court reversal of HHS's decision to exclude, the first such reported case in which a district court overturned such an agency exclusion action.
  • Representing a health care company in preventing a federal regulatory agency from disclosing confidential company business information in response to a freedom of information act (FOIA) request.
  • Representing a not-for-profit organization in defeating a request to provide documents and discovery to a foreign litigant seeking the discovery through the United States federal district court and successfully defending the win before the federal court of appeals.
  • Representing an industry trade associate in the court of appeals in challenges to new EPA air regulations related to greenhouse gas emissions.
  • Counseling a utility on its compliance program related to avian protection.
  • Counseling a real estate developer in opposing a Fish and Wildlife Service proposal to designate company-owned land as critical habitat for endangered species, successfully persuading the Service to substantially reduce the acreage designated.
  • Counseling a mining company regarding its successful application to secure mining rights on land owned by the Bureau of Land Management and abutting areas with sensitive species, including in providing comments related to the proposed environmental impact statement and associated proposed mitigation requirements.
  • Representing a public owned utility in federal court First Amendment litigation over whether the utility's poles should be made available to post attachments requested by a local religious organization and opposed by local municipal authorities.
  • Performing due diligence related to multiple compliance areas in transactions related to energy, manufacturing, and chemical facilities.


  • University of Virginia School of Law, 1990, J.D.
  • Oxford University, Balliol College, 1987, B.A.
  • Michigan State University, 1985, B.A., With High Honors