Thomas A. Lorenzen

Overview

Environmental and climate-related regulations pose substantial challenges and increasingly present significant competitive opportunities for companies doing business in the United States. With over a decade’s experience at the Department of Justice supervising the legal defense of all Environmental Protection Agency regulations, Tom Lorenzen has a deep understanding of both the federal rulemaking process and the limits of EPA’s regulatory authority. That’s why major U.S. corporations and trade associations turn to Tom to help them shape those regulations before they’re finalized, to challenge or defend them in court when they are issued, and to resolve compliance issues once they are operative.

Tom is a trusted adviser to clients seeking to successfully navigate the federal environmental rulemaking process. With a decade of Justice Department experience as the assistant chief responsible for supervising the legal defense of all EPA regulations and other final agency actions in the federal Courts of Appeals and the Supreme Court, he has a unique ability to help his clients shape environmental policy and provide vital input on proposed federal environmental regulations through written comment and direct interaction with federal environmental regulators, many of whom are his former clients or colleagues.

Tom is also known for his extensive appellate and administrative law experience, which he brings to bear when his clients choose to challenge the EPA’s and other agencies’ regulations in court, and increasingly when they seek to defend regulations that they determine present opportunities for their businesses. Tom has litigated or supervised challenges arising under virtually every federal environmental statute, including the Clean Air Act; Clean Water Act; Safe Drinking Water Act; Comprehensive Environmental Response, Compensation, and Liability Act; Federal Insecticide, Fungicide, and Rodenticide Act; Toxic Substance Control Act; National Environmental Policy Act; and Endangered Species Act.

Tom also helps his clients resolve issues of compliance once those regulations are in place, whether by aiding in the conduct of internal compliance audits, responding to agency requests for information regarding compliance with environmental laws and regulations, or resolving allegations of noncompliance.

Tom is a member of Crowell’s Environment and Natural Resources Practice Group and a leader of the firm’s Environmental, Social, and Governance working group. He is one of just four U.S. lawyers ranked as Band 1 in Climate Change Law in 2022 by Chambers and Partners. Tom is a frequent lecturer and commentator regarding federal environmental law, climate change regulation, administrative law, federal policymaking, and effective appellate brief writing and arguments.

Tom is a trusted adviser to clients seeking to successfully navigate the federal environmental rulemaking process. With a decade of Justice Department experience as the assistant chief responsible for supervising the legal defense of all EPA regulations and other final agency actions in the federal Courts of Appeals and the Supreme Court, he has a unique ability to help his clients shape environmental policy and provide vital input on proposed federal environmental regulations through written comment and direct interaction with federal environmental regulators, many of whom are his former clients or colleagues.

Tom is also known for his extensive appellate and administrative law experience, which he brings to bear when his clients choose to challenge the EPA’s and other agencies’ regulations in court, and increasingly when they seek to defend regulations that they determine present opportunities for their businesses. Tom has litigated or supervised challenges arising under virtually every federal environmental statute, including the Clean Air Act; Clean Water Act; Safe Drinking Water Act; Comprehensive Environmental Response, Compensation, and Liability Act; Federal Insecticide, Fungicide, and Rodenticide Act; Toxic Substance Control Act; National Environmental Policy Act; and Endangered Species Act.

Tom also helps his clients resolve issues of compliance once those regulations are in place, whether by aiding in the conduct of internal compliance audits, responding to agency requests for information regarding compliance with environmental laws and regulations, or resolving allegations of noncompliance.

Tom is a member of Crowell’s Environment and Natural Resources Practice Group and a leader of the firm’s Environmental, Social, and Governance working group. He is one of just four U.S. lawyers ranked as Band 1 in Climate Change Law in 2022 by Chambers and Partners. Tom is a frequent lecturer and commentator regarding federal environmental law, climate change regulation, administrative law, federal policymaking, and effective appellate brief writing and arguments.

Career & Education

Department of Justice: Environment and Natural Resources Division
Assistant Chief, Environmental Defense Section, 2004–2013
Senior Counsel for Appellate Matters, Environmental Defense Section, 2000–2004
Trial Attorney, Environmental Defense Section, 1997–2000
- Department of Justice: Environment and Natural Resources Division
  Assistant Chief, Environmental Defense Section, 2004–2013
  Senior Counsel for Appellate Matters, Environmental Defense Section, 2000–2004
  Trial Attorney, Environmental Defense Section, 1997–2000
University of California, Los Angeles, B.A., 1982
Harvard Law School, J.D., 1985
- University of California, Los Angeles, B.A., 1982
- Harvard Law School, J.D., 1985
District of Columbia
- District of Columbia
Professional Activities and Memberships

Member, Editorial Board, Trends newsletter, published by the American Bar Association, Section on Environment, Energy, and Resources, 2015–Present

Co–Chair, American Bar Association, Science & Technology Section, GreenTech and Climate Change Committee, 2017–2021

Steering Committee Member and Co–Chair, District of Columbia Bar, Administrative Law and Agency Practice Community, 2017–Present

Chair, Young Lawyers Section, Bar Association of the District of Columbia, 1996–1997

Secretary, Bar Association of the District of Columbia, 1997–1999

Elected Council Member, Town of Glen Echo, Maryland, 2001–2003
Professional Activities and Memberships
- Member, Editorial Board, Trends newsletter, published by the American Bar Association, Section on Environment, Energy, and Resources, 2015–Present
- Co–Chair, American Bar Association, Science & Technology Section, GreenTech and Climate Change Committee, 2017–2021
- Steering Committee Member and Co–Chair, District of Columbia Bar, Administrative Law and Agency Practice Community, 2017–Present
- Chair, Young Lawyers Section, Bar Association of the District of Columbia, 1996–1997
- Secretary, Bar Association of the District of Columbia, 1997–1999
- Elected Council Member, Town of Glen Echo, Maryland, 2001–2003

Thomas's Insights

Press Coverage | 03.19.25

What Gutting EPA’s Science Office Means For Regulations

Press Coverage | 03.13.25
EPA Staff Cuts Could Jeopardize Broad Deregulatory Push, Observers Say
Press Coverage | 03.13.25
EPA's Deregulation Road Riddled With Potential Potholes
Press Coverage | 10.09.24
Record-Keeping Snafu Puts Texas Haze Control Rule At Risk

View All Insights

Representative Matters

Edison Electric Institute and National Association of Clean Water Agencies – authored Supreme Court amicus brief urging Court to preserve EPA’s authority to regulate greenhouse gases under the Clean Air Act and offering an alternative construction of the “major questions doctrine” that would allow the Court to do so.
National Rural Electric Cooperative Association – provided counsel on EPA's new—and existing—source power plant greenhouse gas emission standards; Tom served as one of the coordinating counsel for the overall challenge to the last Administration's Clean Power Plan, helped to obtain an extraordinary Supreme Court stay of the rule in February 2016, and argued a portion of the case before the D.C. Circuit, sitting en banc, on September 27, 2016. He also served as one of the coordinating counsel for industry and state intervenors supporting EPA’s Affordable Clean Energy Rule and was the principal author of one of the briefs that industry and the states filed in support of that rule.
Edison Electric Institute – authored 8th Circuit and 10th Circuit amicus briefs challenging EPA’s implementation of the Clean Air Act’s regional haze provisions; provides counsel regarding preservation of the Mercury and Air Toxics Standards (MATS) and general Clean Air Act and administrative law issues.
American Fuel & Petrochemical Manufacturers Association – represents AFPM in multiple D.C. Circuit cases regarding EPA’s renewable fuel standards and ozone national ambient air quality standards.
The Chemours Company – represented Chemours in D.C. Circuit litigation regarding listing and delisting of substitutes for ozone-depleting substances. In the most recent challenge to the EPA rules, Tom presented the sole oral argument in support of the rule for both industry and the Natural Resources Defense Council after the Trump administration withdrew its support for the rule.
Provided counsel to major telecommunications company regarding national emission standards for hazardous air pollutants emitted by reciprocating internal combustion engines.
Provided counsel and prepared written comments for multiple trade associations on EPA's new source performance standards for power plant greenhouse gas emissions, EPA's proposed air quality standards for ozone, EPA's appropriate-and-necessary determination for its Mercury and Air Toxics Standards, and its Waters of the United States rule.
Provided counsel to automobile manufacturer and others on compliance with motor vehicle emission control regulations.
Provides counsel to and drafted comments for a major aircraft manufacturer supporting the issuance of a domestic aircraft GHG emission standard.
Prepared comments for trade association on EPA’s proposed CERCLA section 108(b) financial assurance requirements.