Massachusetts v. Environmental Protection Agency
The Court ruled that Massachusetts had legal standing to challenge the EPA's refusal to regulate greenhouse gases from new cars, and that the Clean Air Act's broad definition of "air pollutant" covers carbon dioxide and other greenhouse gases.
The decision rejected the EPA's reasons for declining to regulate and sent the matter back to the agency, opening the door to federal regulation of greenhouse gases as a form of air pollution for the first time.
How it got here: The EPA denied the rulemaking petition; a divided D.C. Circuit panel denied review; Massachusetts and other petitioners sought Supreme Court review.
The Case in Depth
What happened
A coalition of states, local governments, and environmental organizations petitioned the EPA in 1999 to regulate greenhouse gas emissions, including carbon dioxide, from new motor vehicles under the Clean Air Act. The EPA denied the petition, concluding it lacked authority to regulate greenhouse gases and that, even if it had authority, doing so would be unwise given scientific uncertainty and the President's preferred voluntary approach to climate change.
The question before the Court
Could Massachusetts and other states sue to force the EPA to decide whether carbon dioxide from new cars counts as air pollution it must regulate?
Why it matters
The ruling gave states, environmental groups, and future administrations a legal foothold to push the EPA to regulate carbon dioxide and other greenhouse gases from vehicles and other sources. It shaped years of subsequent EPA rulemaking on climate change and confirmed that states suing over widely shared harms like global warming can still get into federal court.
What changes now
The case returns to the EPA, which must reconsider the 1999 rulemaking petition using only statutorily permissible reasons: either finding that greenhouse gases do not endanger public health, or explaining that scientific uncertainty is too deep to make that judgment. The Court expressly left open whether EPA must ultimately find endangerment, or whether policy considerations could factor in if it does. The ruling is a final decision on the legal questions presented, not a temporary order.
What this does not decide
The Court did not decide whether the EPA must actually find that greenhouse gases endanger public health, or whether policy considerations can influence the EPA's decision if it does make such a finding. It held only that the EPA's stated reasons for refusing to decide the question were not grounded in the statute.
Concurrences and dissents
Dissent — Justice Roberts
“Today’s decision is SCRAP for a new generation.”Roberts comparing the majority's standing analysis to a 1973 case seen as the high-water mark of loose standing rules.
Chief Justice Roberts argued the case should have been dismissed for lack of standing. He rejected the majority's idea that states get "special solicitude" in standing analysis, arguing this had no basis in precedent and that Georgia v. Tennessee Copper Co. was about remedies available to states, not Article III standing. He also argued Massachusetts's claimed injury -- coastal land loss -- was too speculative and too weakly tied to EPA's inaction to satisfy the causation and redressability requirements.
Dissent — Justice Scalia
Justice Scalia joined the Chief Justice's dissent in full and wrote separately to dissent on the merits. He argued that EPA reasonably read 'air pollutant' to require something that qualifies as an 'agent' of ground-level air pollution, not just any airborne substance, and that greenhouse gases dispersed throughout the upper atmosphere don't fit that category. He also argued EPA's stated policy reasons for declining to regulate were a permissible exercise of its discretion under the statute's silence on that question.
How the Court got there
The legal reasoning, step by step
- The Court first addressed whether any petitioner had legal standing to sue, applying the requirement that a challenger show a concrete injury, a causal link to the government's conduct, and a likelihood that a court win would fix the problem. It concluded that because Massachusetts is a state with a procedural right under the Clean Air Act to challenge EPA's rulemaking denial, and because it owns coastal land threatened by rising seas, it deserved special consideration in this standing analysis.
- Applying that framework, the Court found Massachusetts's injury (loss of coastal land from rising seas), causation (EPA's admitted failure to dispute that greenhouse gases cause warming), and redressability (a reasonable chance that regulation would slow emissions) were all satisfied, even though the harm of global warming is shared widely by everyone.
- Turning to the merits, the Court read the Clean Air Act's definition of 'air pollutant' -- which sweeps in 'any physical, chemical... substance' entering the air -- to plainly include carbon dioxide and other greenhouse gases, rejecting the EPA's argument that Congress meant to exclude them.
- The Court rejected the EPA's reliance on Congress's failure to pass later climate legislation as evidence that the agency lacked authority, reasoning that what a later Congress chose not to do says little about what an earlier Congress meant when it wrote the statute.
- Because the statute ties EPA's authority to a scientific 'judgment' about whether a pollutant endangers public health, the Court held that EPA could not decline to act based on policy preferences like protecting the President's diplomatic flexibility; it could only decline to regulate by finding no endangerment or by explaining that the science was too uncertain to judge at all.
- Since EPA's stated reasons were policy-based rather than a genuine finding on the science, the Court concluded EPA's denial of the petition was not adequately grounded in the statute.
Doctrinal impact
Cases affected by this decision
Distinguishes FDA v. Brown & Williamson Tobacco Corp. (529 U. S. 120)
The Court said the tobacco case's reasoning didn't apply because EPA regulation would not force any extreme ban like the FDCA would have.
Distinguishes Heckler v. Chaney (470 U. S. 821)
The Court said the rule that agencies' enforcement refusals escape review doesn't apply to a formal denial of a rulemaking petition.