Foundations of the Endangerment Finding

• Pages: 7-17
• Date: 01 July 2025
• Published date: 01 July 2025
• Author: Jonathan Cannon, Phil Duffy, and Lisa Heinzerling
• Subject Matter: Administrative & Public Law

JULY/AUGUST 2025 ENVIRONMENTAL LAW REPORTER 55 ELR 10359

DIALOGUE

FOUNDATIONS OF THE

ENDANGERMENT FINDING

In 2009, the U.S. Environmental Protection Agency (EPA) published what is commonly referred to as the

“endangerment f‌inding.” Prompted by the U.S. Supreme Court’s landmark decision in Massachusetts v. Envi-

ronmental Protection Agency (2007) and ref‌lecting robust science, the f‌inding deter mined that six key green-

house gases qualify as air pollution under the Clean Air Act and pose a threat to the health and welfare of

future generations. This authorized EPA to set emissions standards for motor vehicles an d other major sources

of greenhouse gases; however, the Agency recently announced the f‌inding will undergo reconsideration of

whether it “complies with the law and is based on sound science and policy.” On May 22, 2025, the Environ-

mental Law Institute hosted a panel of experts to discuss the legal and scientif‌ic f oundations of the endanger-

ment f‌inding. Below, we present a transcript of that discussion, which has been edited for style, clarit y, and

space considerations.

SUMMARYSUMMARY

Sarah Vican is Manager of Educational Programs at the

Environmental Law Institute.

Jonathan Cannon is the Blaine T. Phillips Distinguished

Professor of Environmental Law emeritus at the University

of Virginia School of Law.

Phil Du y is Chief Scientist at Spark Climate Solutions.

Lisa Heinzerling is the Justice William J. Brennan Jr.

Professor of Law at Georgetown Law.

Sarah Vican: Our moderator, Jonathan Cannon, is the

Blaine T. Phillips Distinguished Professor of Environ-

mental Law emeritus at the University of Virginia (UVA)

School of Law. He joined the UVA law faculty in 1998

after a disting uished career at the U.S. Environmental Pro-

tection Agency (EPA) in addition to private practice. He

is founding director of the law school’s Program in Law,

Communities, and the Environment.

Jonathan Cannon: anks so much. With me are our

expert panelists, who wi ll help us navigate the strengt hs

and possible vulnerabilities of EPA’s 2009 endangerment

nding for greenhouse gas (GHG) emissions.1 at nd ing

is the linchpin of EPA’s authority to regulate these emis-

sions from domestic sources.

In March of this year, EPA Administrator Lee Z eldin

put a bullseye on that nding, vowing to “driv[e] a dag-

ger straight into the heart of the climate change religion.”2

1. Endangerment and Cause or Contribute Findings for Greenhouse Gases Un-

der Section 202(a) of the Clean Air Act, 74 Fed. Reg. 66496 (Dec. 15, 2009).

2. Press Release, U.S. EPA, EPA Launches Biggest Deregulatory Action in

U.S. History (Mar. 12, 2025), https://www.epa.gov/newsreleases/epa-

launches-biggest-deregulatory-action-us-history.

It’s a full inversion of science and religion, as my friend

Bob Sussman has pointed out. e question today for our

panel is, is this a vow that Zeldin has any reasonable hope

of keeping?

Dr. Phil Duy is a climate scientist who now serves

as the chief scientist at Spark Climate Solutions. He was

previously a senior adviser in the White House Oce of

Science and Technology Policy i n the Joseph Biden and

Barack Obama Administrations, and has held other senior

positions in government as well as in climate-oriented non-

governmental organizations. He has w ritten on the risks of

climate change, and is t he lead author of a 2019 article in

the journa l Science summarizing how science oers even

stronger support for the endangerment nding that EPA

had issued 10 years earlier.3

Lisa Heinzerling is the Justice William J. Brennan Jr.

Professor of Law at Georgetown Law Center, a leading

environmental law scholar, and also a gifted advocate. She

was a principal draf ter of the briefs in Massachusetts v. Envi-

ronmental Protection Agency4 that made the successfu l case

for regulation of GHGs under the Clean Air Act (CA A),

paving the way for the endangerment nding of 2009 and

the EPA climate rules that followed. With Phil, Lisa is a co-

author of the Science article on the endangerment  nding,

and she has written extensively on regulations in admin-

istrative practice and statutory interpretation by the U.S.

Supreme Court.

3. Philip B. Duy et al., Strengthened Scientic Support for the Endangerment

Finding for Atmospheric Greenhouse Gases, 363 S eaat5982 (2019),

https://www.science.org/doi/pdf/10.1126/science.aat5982.

4. 549 U.S. 497 (2007).

Copyright © 2025 Environmental Law Institute®, Washington, DC. Reprinted with permission from ELR®, http://www.eli.org