Image by Olavi Anttila from Pixabay
Through multiple actions, Attorney General Bonta and multistate partners, stand up for climate science, oppose EPA’s proposal to repeal all the federal motor vehicle greenhouse gas emission standards that protect the health and safety of Americans
September 22, 2025 - OAKLAND – California Attorney General Rob Bonta today co-led a coalition of 23 attorneys general and seven counties and cities in filing a comment letter opposing the U.S. Environmental Protection Agency’s (EPA) proposed rescission of its landmark 2009 finding that greenhouse gas emissions, including from motor vehicles, drive climate change and endanger public health and welfare. This finding is known as the Endangerment Finding. Last month, the Trump Administration announced its proposal to rescind the Endangerment Finding, claiming that EPA lacks authority to regulate greenhouse gas emissions that contribute to climate change, as well as to eliminate all existing EPA greenhouse gas emission standards for vehicles.
“The EPA’s rescission proposal is not just a step backward — it is a dangerous retreat from science and the law,” said Attorney General Bonta. “To suggest that greenhouse gas emissions don’t endanger public health is absolutely reckless. Let’s be clear: This proposed rollback does not serve the public. It serves bad actor polluters. It prioritizes fossil fuel interests over scientific truth. It puts short-term oil profits ahead of public health and combatting climate change. We cannot allow it; the stakes are too high. We urge the EPA to withdraw this proposal.”
The 2009 Endangerment Finding was the direct result of the landmark 2007 Supreme Court opinion in Massachusetts v. EPA, which confirmed EPA’s authority under the Clean Air Act to regulate greenhouse gas emissions that threaten public health and welfare. In direct response to that opinion, and after more than two years of scientific review, EPA determined in 2009 that greenhouse gas emissions from motor vehicles contribute to climate change that harms public health and welfare in numerous ways.
As the National Academies of Sciences, Engineering, and Medicine confirmed just last week, “EPA’s 2009 finding that the human-caused emissions of greenhouse gases threaten human health and welfare was accurate, has stood the test of time, and is now reinforced by even stronger evidence.” EPA’s new proposal, which relies on a flawed, unlawful, and unfinished report issued by a handful of climate deniers handpicked by the Secretary of Energy — the so-called “Climate Working Group”— seeks to reverse that finding with no grounding in law or science.
Today’s comment letter builds on the coalition’s efforts to fight back against EPA’s dangerous proposal.
Endangerment Finding Comment Letter
In today’s letter, the coalition argues that rescinding the Endangerment Finding would violate settled law, Supreme Court precedent, and scientific consensus, endangering the lives of hundreds of millions of Americans, particularly those in communities disproportionately impacted by environmental harms.
Scientific research has proven that every region of our country, and especially California, is experiencing the ongoing and significant harms of climate change and motor vehicle pollution, including changes in temperature, precipitation, and sea level rise. Extreme summer heat, driven by climate change, is leading to increased rates of heat-related illness and death, particularly among vulnerable populations like children, the elderly, low-income individuals, and workers. Increasing rates of natural disasters – like wildfires, hurricanes, flooding, and droughts – not only have a devastating effect on public health and safety, but on state and local economies as well.
Not only does EPA’s proposed rescission ignore those facts, which are backed by robust climate science, but it also violates EPA’s legal obligations under the federal Clean Air Act to regulate greenhouse gas emissions to address climate change. The coalition argues that EPA’s new legal interpretations are fundamentally inconsistent with the Clean Air Act and binding Supreme Court precedent, and that the proposal would mark a drastic reversal of its own longstanding findings without any explanation grounded in science. To make matters worse, the Climate Working Group report on which EPA relies is procedurally and substantively flawed, yet EPA accepts its findings and disregards the scientific consensus, which was just reaffirmed by the National Academies last week.
In filing this comment letter, the coalition urges EPA to abandon its unlawful and unsupported proposal to rescind the Endangerment Finding.
Attorney General Bonta co-led this letter alongside attorneys general of Connecticut, Massachusetts and New York. The coalition includes the attorneys general of Arizona, Colorado, Delaware, the District of Columbia, Hawaii, Illinois, Maine, Maryland, Michigan, Minnesota, Nevada, New Jersey, New Mexico, North Carolina, Oregon, Rhode Island, Vermont, Washington, and Wisconsin; the Cities of Chicago, New York, and Oakland; the City and County of Denver; and the Counties of Martin Luther King Jr., the City and County of San Francisco, California; and the County of Santa Clara, California.
A copy of the letter can be found here.
Motor Vehicles Comment Letter
In withdrawing the 2009 Endangerment Finding, EPA also proposes to repeal all existing federal greenhouse gas emissions standards for all motor vehicle classes and all years. In a second letter submitted to the EPA today, the coalition explains that this unprecedented disruption to the regulatory landscape of the last 15 years will be catastrophic for the States' and local governments’ residents, industries, natural resources, and public investments. For instance, EPA projected last year that current motor vehicle greenhouse gas emissions standards would prevent more than 8 billion metric tons of CO2-equivalent greenhouse gas emissions over the next 30 years, avoiding $1.82 trillion in climate harms. If those reductions from the federal motor vehicle greenhouse gas program, alone, were the emissions of a country, that country would rank No. 33 on a list of the world’s top emitters.
A robust regulatory program for greenhouse gas emissions is also crucial to vehicle affordability, consumer choice, and the success of the American automotive industry. The greenhouse gas program for vehicles spurs automakers to innovate and create better cars, saving drivers hundreds of billions of dollars in fuel and maintenance costs, and helps support domestic manufacturing and jobs. Repealing that program, as EPA now proposes, will shutter factories, kill jobs, and wipe out billions of dollars in investments by Congress, States, and local governments to keep the American auto industry thriving and globally competitive. The best way to support drivers and auto workers — while also helping the planet — isn’t to protect the President’s fossil-fuel friends, but to continue promoting innovation in the most cutting-edge vehicle technologies.
Attorney General Bonta leads the attorneys general of Arizona, Colorado, Connecticut, Delaware, Hawai‘i, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, Nevada, New Jersey, New Mexico, New York, North Carolina, Oregon, Rhode Island, Vermont, Washington, Wisconsin, and the District of Columbia; and the Chief Legal Officers of the City of Chicago, Illinois; the City of New York, New York; the City of Oakland, California; Martin Luther King, Jr. County, Washington; the City and County of Denver, Colorado; the City and County of San Francisco, California; and the County of Santa Clara, California
A copy of the letter can be found here.
Climate Working Group Comment Letter
On September 2, Attorney General Bonta joined a coalition of 22 attorneys general, three cities, and two counties in filing a comment letter opposing the Climate Working Group (CWG) report that EPA relied on in its proposed rescission of the Endangerment Finding.
In that comment letter, the coalition identified numerous procedural and substantive legal flaws in the CWG report. In creating the CWG, the Department of Energy selected five widely known climate change deniers, ignored well-established scientific integrity standards, and failed to comply with Federal Advisory Committee Act (FACA) procedures, which require the disclosure of all committee-related records and that committee meetings be open to the public.
The report explicitly sought to contradict mainstream climate science. It was written in less than two months and riddled with inaccuracies, factual omissions, and mischaracterizations of irrefutable climate science research — weak attempts to undermine decades of peer-reviewed scientific research establishing that the emission of greenhouse gases causes climate change and endangers public health and welfare.
In filing the comment letter, the coalition urged the Department of Energy to withdraw the unlawful and misguided CWG report.
Joining Attorney General Bonta in filing the comment letter, which was co-led by the attorneys general of Massachusetts and New York, were the attorneys general of Arizona, California, Connecticut, Colorado, Delaware, the District of Columbia, Hawaii, Illinois, Maine, Maryland, Michigan, Minnesota, New Jersey, New Mexico, North Carolina, Oregon, Rhode Island, Vermont, Washington, Wisconsin, and the Chief Legal Officers of the City and County of Denver, Martin Luther King Jr. County, Washington, and the Cities of Chicago and New York.
Climate Working Group Amicus Brief
On August 29, Attorney General Bonta joined a coalition of 19 attorneys general and the City of New York in filing an amicus brief in the U.S. District Court for the District of Massachusetts in Environmental Defense Fund v. Wright, supporting the plaintiffs in their effort to declare the Climate Working Group’s report unlawful.
In their brief, the coalition argued that the Department of Energy violated FACA by establishing and utilizing the Climate Working Group, and that this violation will harm state and local governments’ strong interest in ensuring that the federal government rely on the best available science to guide its climate policy decisions.
On September 17, the Court held that the Climate Working Group is not exempt from FACA.
Joining Attorney General Bonta in filing this amicus brief, which was led by the attorney general of Massachusetts, were the attorneys general of California, Colorado, Connecticut, Delaware, the District of Columbia, Hawaii, Illinois, Maine, Maryland, Michigan, Minnesota, New Jersey, New Mexico, New York, Oregon, Vermont, Washington, Wisconsin, and the City of New York.
In addition to the actions described above, Attorney General Bonta testified before EPA last month to oppose its proposed rescission of the 2009 Endangerment Finding and motor vehicle greenhouse gas standards. His remarks can be found here.
Source: CA. DOJ
