This educational guide is based on the linked primary sources. It is not a Court publication, is not affiliated with the Court, and is not legal advice.
In brief
Overview
According to James R. Milkey, on behalf of the Petitioners, the petitioners argue that the EPA has room to act based on the endangerment standard and general principles of administrative law.
According to Gregory G. Garre, the respondents contend that Congress has not authorized the EPA to regulate greenhouse‑gas emissions and that scientific uncertainty makes regulation premature.
Background and question before the Court
According to James R. Milkey, on behalf of the Petitioners, the petitioners frame the case as one of ordinary statutory interpretation and administrative law.
Justice Scalia asked whether the alleged harm to the state is imminent, a requirement for standing.
According to Justice Alito, justice Alito questioned whether the EPA could decline to regulate an air pollutant if it concluded regulation would endanger public health and welfare.
Justice Alito also asked whether the definition of public welfare is extremely broad.
What each side argues
Petitioners (Massachusetts)
According to James R. Milkey, on behalf of the Petitioners, the petitioners argue that the case turns on ordinary principles of statutory interpretation and administrative law.
According to James R. Milkey, on behalf of the Petitioners, congress expressly referred to carbon dioxide as an air pollutant, so it is an air‑pollution agent.
According to James R. Milkey, on behalf of the Petitioners, EPA has considerable discretion under the endangerment standard and general administrative‑law principles.
According to Mr. Milkey, the acid‑rain analogy shows that a pollutant’s harm can occur after it leaves the air, so regulation is appropriate.
Respondents (EPA)
According to Gregory G. Garre, congress has not authorized the EPA to regulate greenhouse‑gas emissions to address global climate change.
According to EPA, the Court’s precedents (Lujan v. Defenders of Wildlife; ASARCO v. Kadish) show that standing cannot be based on speculative future harms caused by independent actors.
What happened at oral argument
Oral argument before the Supreme Court began at 10:02 a.m.
What the Court decided
Why it matters
Terms to know
No glossary terms are available for this guide.
Primary sources
Read the source materials on the official site or open the immutable repository copy used for this guide.
- 4f9671e64cfca142e75c-r1-c08ac479a8f8432f.pdforal argument transcript
Guide generated September 21, 2026. Automated validation accepted this version.