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Ronald J. Tenpas
Ronald J. Tenpas
Partner — Environmental & Natural Resources
Partner — Environmental & Natural Resources

Ronald J. Tenpas

Ronald J. Tenpas

2200 Pennsylvania Avenue NW
Suite 500 West
Washington, DC 20037

start quote symbolMy Justice Department experience helps clients make smart decisions about when to look to settle, and when to fight.end quote symbol
Ronald J. Tenpas

Ron Tenpas is one of the country’s preeminent environmental litigators. A former Assistant Attorney General (AAG) for the Environment and Natural Resources Division of the U.S. Department of Justice, Ron represents clients in civil and criminal investigations related to alleged environmental violations, imports and other matters. He also represents companies and trade associations in commenting on proposed regulations and in litigation challenging new regulatory provisions.

In counseling clients, Ron draws upon 12 years of experience in the Justice Department. As AAG, a title he held from 2007 until 2009, he managed a 700-person division that included 400 lawyers. He oversaw civil and criminal litigation arising under more than 150 environmental and natural resources laws.

In addition, as AAG Ron defended the government when the government was sued in connection with its own use of natural resources. Ron also advised Cabinet and White House officials on policy and litigation risks associated with the environmental laws. Under Ron’s watch, the Justice Department secured what was at the time the largest criminal penalty under the Clean Air Act.

Before he was appointed AAG, Ron 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. He investigated and tried white-collar matters related to healthcare fraud and public corruption.

A Rhodes Scholar and editor-in-chief of the Virginia Law Review, Ron served as a clerk to Chief Justice William H. Rehnquist of the U.S. Supreme Court.

Ron’s environmental practice has been recognized by Chambers USA. A source quoted by Chambers said Ron has “a unique combination of being a skilled environmental lawyer and being able to clearly communicate to his clients and develop a path forward” (2019).

Experience Highlights

  • Representing an oil and gas services 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 pipeline inspection company in a criminal investigation related to improper inspections; secured declination of criminal charges

  • Representing a publicly-traded shipping company in connection with alleged oil pollution and false record-keeping; secured declination of charges against parent holding company

  • Representing company employees in a criminal investigation of illegal wood imports

  • 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 foreign ATV and motorcycle manufacturers in successfully resolving alleged violations related to the import of non-conforming products under the Clean Air Act, including securing conditions allowing the companies to continue or 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

  • Representing a food logistics company and a beverage manufacturer before the EPA on claims that chemical spills were not timely reported to federal and state agencies

  • 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’s chief administrative law judge and before the agency appeals board regarding allegations that the company failed to report alleged adverse risk information, securing a complete dismissal of the administrative complaint and the agencies proposed multi-million dollar penalty

  • Representing a biofuels producer in a civil proceeding alleging violations of the EPA’s renewable fuels mandates and credit trading regime

  • 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 chemical and refining companies in asserting confidential business information claims to protect information under FOIA

  • Representing a not-for-profit organization in defeating a request to provide documents and discovery to a foreign litigant seeking the discovery through the US federal district court and successfully defending the win before the federal court of appeals

  • Representing an industry trade associate in a successful court of appeals and Supreme Court challenge 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 publicly 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.
  • University of Oxford, Balliol College, 1987, B.A.
  • Michigan State University, 1985, B.A., with high honors
  • Assistant Attorney General, U.S. Department of Justice, Environment and Natural Resources Division, Environmental Enforcement Section, 2007 – 2009
  • Associate Deputy Attorney General, U.S. Department of Justice, Environment and Natural Resources Division, Environmental Enforcement Section, 2005 – 2007
  • United States Attorney, U.S. Attorney’s Office for the Southern District of Illinois, 2003 – 2005
  • Assistant United States Attorney, U.S. Attorney’s Office for the District of Maryland, 1999 – 2003
  • Assistant United States Attorney, U.S. Attorney’s Office for the Middle District of Florida, 1997 – 1999
  • Judicial clerk to The Honorable Howard Holtzmann, Iran-United States Claims Tribunal – The Hague, Netherlands, 1992 – 1993
  • Judicial clerk to The Honorable William H. Rehnquist, Chief Justice, U.S. Supreme Court, 1991 – 1992
  • Judicial clerk to The Honorable Judge Louis H. Pollak, U.S. District Court for the Eastern District of Pennsylvania, 1990 – 1991
  • Chambers USA, Environment (District of Columbia), 2011–2020
  • The Best Lawyers in America© (BL Rankings, LLC), Litigation – Environmental, 2017–2021
  • Legal 500 U.S., Environment: Litigation, 2014, 2016, 2019; Corporate Investigations and White-Collar Criminal Defense, 2019; Environment: Regulatory, 2019
  • Who’s Who Legal (Law Business Research Ltd.), Environment, 2016
  • U.S. Department of Justice, Edmund J. Randolph Award for Outstanding Service, 2009
  • Selected to the Washington, D.C. Super Lawyers list, Super Lawyers (Thomson Reuters), 2020
  • Secretary of the Navy, Distinguished Service Award
  • Global Investigations Review (GIR) 100, 2020
  • Council Member: American Bar Association, Section of Public Utility, Communications and Transportation (PUCAT); Chair: Environment Committee
  • Member: American Association of Rhodes Scholars
  • District of Columbia
  • Maryland