EPA’s Vehicle Emissions Regulation U-Turn Defies Supreme Court

The Environmental Protection Agency is slamming the brakes on years of effort to control greenhouse gas emissions from cars and trucks. For 15 years, across both Democratic and Republican administrations, including the first Trump administration, the EPA has regulated greenhouse gas emissions from motor vehicles.

But in a new proposal, the agency argues it was mistaken all along. The agency is advancing a brand new “best” interpretation of Section 202(a) of the Clean Air Act that would foreclose its authority over greenhouse gas emissions that contribute to climate change. The agency is arguing its authority extends only to pollutants that endanger the public through “local or regional exposure,” and that even if it did have broader authority, regulation would be “futile” given the scale of global climate change.

But the EPA’s legal arguments stall out with errors and inconsistencies.

First, the EPA points to the US Supreme Court’s recent opinion in Loper Bright v. Raimondo as a key reason to disrupt its status quo. But Loper Bright does just the opposite.

In Loper Bright, the Supreme Court said statutes ‘‘have a single, best meaning’’ most properly discerned by judges. In its new proposal, the EPA purports to have only now discovered what that best meaning is for Section 202(a). However, in 2007, the Supreme Court already interpreted the meaning of that provision in the landmark climate case, Massachusetts v. EPA. Spoiler: it doesn’t match up with the EPA’s latest read.

In Massachusetts, the court confirmed greenhouse gas emissions “unambiguously” fall under Section 202(a) of the Clean Air Act. The court further instructed that the EPA must regulate motor vehicle greenhouse gas emissions if the agency finds they “cause, or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare.”

Two years later, the EPA made such an endangerment and contribution finding based on extensive, peer-reviewed scientific evidence, and thousands of public comments. In the years since, the science has only grown stronger, and the effects of climate change have become the new normal in the form of rampant wildfires, devastating hurricanes, and deadly heatwaves.

The finding has also survived legal challenge in the courts, and the Obama, Trump I, and Biden administrations each denied petitions for its reconsideration.

Second, the EPA argues that regulating greenhouse gases from cars would implicate the “major questions doctrine,” claiming that Section 202(a) doesn’t provide clear authorization from Congress to address climate concerns. But here again, the EPA runs into a roadblock from Massachusetts.

There, the EPA made principally the same argument and the court rejected it, finding “no reason, much less a compelling reason, to accept EPA’s invitation to read ambiguity into a clear statute” and noting “there is nothing counterintuitive to the notion that EPA can curtail the emission of substances that are putting the global climate out of kilter.”

Third, the EPA finds that motor vehicle greenhouse gas emissions constitute too “small” of a contribution or that regulation would have “no meaningful impact.” The EPA can’t make these arguments in good faith.

In 2022, motor vehicles alone emitted more than 23% of overall greenhouse gas emissions in the US. The US vehicle sector is also the highest source of transportation emissions globally—over the last 50 years, US vehicles have emitted more greenhouse gases than the vehicles in the next nine highest-emitting countries combined.

Using the EPA’s damages estimates, a single year’s worth of emissions from the existing fleet of US on-road vehicles will lead to nearly $350 billion in total global damages. This includes an estimated $215 billion in global health damages and an estimated $72 billion in lost labor productivity due to decreased work-hours in extreme temperatures.

Further, the EPA has historically found that vehicles responsible for far smaller shares of pollution than cars and trucks “contribute” to air pollution for the purpose of the Clean Air Act. This includes motorcycles, which accounted for less than 1% of domestic mobile source emissions of particulate matter, hydrocarbons, and similar pollutants.

A recent report we authored also explains how the legislative history from the Clean Air Act confirms the provision encompasses all sources of pollution—not just those contributions above a certain threshold.

While it’s true that Loper Bright preserved a lane for agency discretion, the court said that discretion can only operate within statutory limits. With Massachusetts, the Supreme Court set statutory guardrails the EPA can’t plow through. When applying discretion within those boundaries, there is no pathway to reasonably conclude anything other than that motor vehicle greenhouse gas emissions contribute to the dangerous effects of climate change.

Fourth, the EPA argues that vehicle emissions standards are too costly to keep on the books. But the Supreme Court has made clear that policy considerations, such as costs, can’t be considered when making an endangerment finding. Instead, costs should be evaluated with benefits as part of the issuance of specific emission limits. The EPA has done that, and its own analyses show that greenhouse gas regulations provide trillions of dollars in net benefits—that is, benefits in excess of regulatory costs.

The agency’s most recent light- and medium-duty vehicle standards, finalized last year, are projected to save consumers more than $800 billion in fuel costs and reduce more than $1.5 trillion in climate-change damages.

Finally, it’s worth noting that in ongoing litigation, the federal government has itself been arguing against certain state-level laws for greenhouse gas emissions by emphasizing that the Clean Air Act “comprehensively regulates nationwide air pollution.” But here the EPA is concurrently arguing that the Clean Air Act doesn’t comprehensively allow it to regulate greenhouse gas emissions. The EPA can’t have it both ways.

The agency is simply choosing whichever argument is more convenient in each context to bail on its obligations.

The law and the facts reveal the truth. The EPA’s new proposal is a junker: inoperable, uneconomic, and ready for the regulatory scrapyard.

This article does not necessarily reflect the opinion of Bloomberg Industry Group, Inc., the publisher of Bloomberg Law, Bloomberg Tax, and Bloomberg Government, or its owners.

Author Information

Dena Adler is a senior attorney and Kate Welty is a legal fellow at NYU School of Law’s Institute for Policy Integrity, a non-partisan think tank dedicated to improving the quality of governmental decision-making.

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