A coalition of public health and environmental groups filed a suit Wednesday challenging the Trump administration’s recent finding that the Environmental Protection Agency could not regulate climate-warming greenhouse gases.

EPA Administrator Lee Zeldin and President Donald Trump announced last week the administration was finalizing a repeal of the 2009 endangerment finding, which declared the agency could regulate greenhouse gas emissions, particularly from vehicle emissions, because climate change posed a danger to human health.

The 17 groups who jointly filed the suit Wednesday include the American Public Health Association, Clean Wisconsin, Union of Concerned Scientists, Earthjustice and Natural Resources Defense Council. 

‘Required by law to protect us’

Their two-page filing in the U.S. Court of Appeals for the D.C. Circuit does not detail any of the groups’ legal arguments against the repeal, but lawyers and officials for the groups said the EPA was legally bound, under the Clean Air Act, to protect people from greenhouse gas emissions. 

“They are required by law to protect us from air pollution that endangers public health and welfare,” Dr. Georges C. Benjamin, the CEO of the American Public Health Association, said on a video call with reporters. “And that includes greenhouse gases that are driving climate change.”

The law requires challenges to new nationwide agency actions on emissions to be filed in the D.C. Circuit.

In an email, EPA press secretary Brigit Hirsch said the agency had reviewed the endangerment finding, the Clean Air Act and related court decisions, including “robust analysis” of recent Supreme Court decisions. The agency concluded it did not have authority to regulate greenhouse gas emissions.

“Unlike our predecessors, the Trump EPA is committed to following the law exactly as it is written and as Congress intended—not as others might wish it to be,” Hirsch said. 

“In the absence of such authority, the Endangerment Finding is not valid, and EPA cannot retain the regulations that resulted from it,” she continued. “EPA is bound by the laws established by Congress, including under the CAA. Congress never intended to give EPA authority to impose GHG regulations for cars and trucks.”

Emissions are pollutants, opponents say

But the groups said the EPA’s reasoning ignored that the agency has long regulated emissions as part of its mandate to protect clear air. The omission of the term “greenhouse gases” in the Clean Air Act is “a manufactured problem” by opponents of regulation, Hana Vizcarra, a senior attorney at Earthjustice, said.

“The Clean Air Act was intended to cover air pollutants, full stop. Air pollutants include greenhouse gases,” she said. “This argument that Congress needs to do something different to be able to regulate greenhouse gases… it’s just a way to avoid the issue and avoid regulation.”

The matter is “settled law,” the groups said, as federal courts have affirmed and reaffirmed the EPA’s power to regulate emissions.

A 2007 U.S. Supreme Court case established that the Clean Air Act “was unambiguous” in authorizing the EPA to regulate greenhouse gases as pollutants, Meredith Hankins, a senior attorney at NRDC, said. 

That decision led to the EPA’s so-called endangerment finding two years later, during President Barack Obama’s first year in office.

Attorneys general likely to weigh in

Wednesday’s challenge will likely be consolidated with other challenges, including those from “blue-state attorneys general,” Hankins said.

In the announcement last week, Trump said the endangerment finding, and the tailpipe emissions standards that relied on it, had dragged down the automotive sector and the broader economy nationwide.

The administration has said the move will save Americans more than $1 trillion by reducing regulations.

The repeal’s opponents, though, said Wednesday that projection ignored more than $100 billion in additional costs American drivers would see if fuel efficiency standards are relaxed or the enormous public health costs from worsened air quality and increased climate risks.

The federal administration’s decision to rescind the Environmental Protection Agency’s Endangerment Finding may sound technical. In reality, it targets the legal foundation that has allowed the United States to regulate climate pollution for more than a decade. For Wisconsin, the move introduces new uncertainty just as communities, farmers and businesses invest in cleaner energy, efficiency and more resilient infrastructure.

The 2009 Endangerment Finding concluded that greenhouse gases threaten public health and welfare. Courts have upheld that determination repeatedly. Eliminating or weakening it does not change the science behind climate change, but it could reshape how power plants, vehicles and industrial facilities are regulated. That shift carries consequences for states already dealing with smoky summers, heavier rainfall and rising infrastructure costs.

Wisconsin’s clean energy economy has expanded steadily, often without much attention. Renewable projects now generate enough electricity to power about 560,000 homes. Roughly 75,000 residents work in clean energy fields, and more than 350 Wisconsin companies supply technologies or services that reduce energy use or emissions. Together, these efforts reflect a broader reality: climate progress here tends to be practical and locally driven because it lowers costs and strengthens communities.

Examples are visible across the state. School districts and municipal buildings are cutting operating expenses through efficiency upgrades supported by Focus on Energy programs. Tribal and low-income households are receiving targeted weatherization investments that improve comfort and reduce utility bills. Builders and manufacturers are adopting higher performance standards to reduce long-term risk.

Federal rollbacks do not automatically halt these efforts, but they complicate financing and planning. Investors and local governments rely on predictable rules. When national standards shift, projects that once appeared viable can stall.

Some of the clearest examples are unfolding in rural Wisconsin. The SolarShare Wisconsin Cooperative is expanding community-owned solar projects that keep energy dollars circulating locally while pairing installations with pollinator habitat or sheep grazing. Hidden Springs Creamery installed a 50-kilowatt solar system to power its creamery and farm operations while continuing to produce artisanal cheeses. These projects reflect a simple idea gaining traction across the state: build it here, power it here, prosper here.

Wisconsin’s dairy sector has also become a testing ground for methane reduction strategies. Anaerobic digesters, renewable natural gas systems and advanced manure management technologies are already operating throughout the state. They reduce emissions while improving water quality and creating new revenue streams for farmers. If federal climate incentives weaken, fewer of these projects may move forward, leaving producers to absorb more risk and potentially slowing innovation that began here.

At the same time, new pressures are emerging from the rapid growth of artificial intelligence and large-scale data centers. Utilities are proposing infrastructure expansions to meet rising electricity demand, raising questions about cost allocation, water use and oversight. Small businesses, tribes, farmers and rural communities are organizing around siting decisions that affect farmland and ratepayers.

This week, the Power Wisconsin Forward campaign, supported by the Clean Economy Coalition of Wisconsin and more than 50 partner organizations, urged the Public Service Commission to ensure that data center costs do not shift onto ordinary customers. The debate highlights a broader reality. Wisconsin’s energy landscape is changing quickly even as federal climate policy moves in the opposite direction.

It would be misleading to suggest Wisconsin’s political environment has become less polarized. Recent legislative sessions show deep divisions and limited consensus on climate priorities. That context makes federal rollbacks more consequential. Without consistent national guardrails, states rely more heavily on local initiatives and market forces, which can advance progress but unevenly.

Legal challenges to the EPA decision are likely, but outcomes remain uncertain. In the meantime, utilities, farmers and local governments must make decisions without clear signals from Washington.

The practical question facing Wisconsin is not whether federal politics will shift. It is whether the state continues investing in projects that already deliver measurable results. Efficiency upgrades lower utility bills. Community solar keeps energy spending local. Methane reduction technologies help farms manage waste while improving soil and water conditions.

In a politically diverse state, climate progress rarely looks dramatic. It often appears as quieter momentum built through local partnerships and incremental gains. The federal rollback raises real risks, but it does not erase the infrastructure or collaboration already underway.

What happens next will be shaped less by national rhetoric and more by decisions made at the Public Service Commission, in county zoning meetings and on working farms across Wisconsin.

WASHINGTON — President Donald Trump and his top environmental policy officer finalized a move Thursday to undo an Environmental Protection Agency regulation that laid the foundation for federal rules governing emissions of the greenhouse gases that cause climate change.

At a White House event, Trump and EPA Administrator Lee Zeldin said they were officially rolling back the “endangerment finding” that labeled greenhouse gases a threat to public health and provided a framework for the EPA to regulate emissions. 

The 2009 finding, established under President Barack Obama, called climate change a danger to human health and therefore gave the EPA power to regulate greenhouse gases, such as carbon dioxide from cars and trucks. 

Such regulations created a challenge for automakers and other industries, which dragged down the entire economy, according to Trump, administration officials and allies in Congress. 

Democrats and their allies in environmental and climate activism, though, consider the measure a crucial tool to address climate change and protect human health.

Undoing the finding will remove the economy-wide uncertainty, Trump argued. 

“That is why, effective immediately, we are repealing the ridiculous endangerment finding and terminating all additional green emission standards imposed unnecessarily on vehicle models and engines between 2012 and 2027 and beyond,” he said Thursday. 

Affordability argument

In its initial notice last year that it would repeal the endangerment finding, the EPA said it did not have the authority to regulate vehicle emissions.

With household costs, including transportation, expected to be a major theme in the fall’s midterm campaigns to determine control of Congress, members of both parties have framed it as an economic issue.

“This will be the largest deregulatory action in American history, and it will save the American people $1.3 trillion in crushing regulations,” White House press secretary Karoline Leavitt said at Tuesday’s press briefing.

Some Democrats and climate activists argue the rollback will hurt the country’s nascent renewable energy sector, driving up the cost of home heating, electricity and other common expenses.

Senate Minority Leader Chuck Schumer, D-N.Y., and Sen. Sheldon Whitehouse, D-R.I., issued a lengthy joint statement slamming the announcement.

“The Trump EPA has fully abandoned its duty to protect the American people from greenhouse gas pollution and climate change.  This shameful abdication — an economic, moral, and political failure — will harm Americans’ health, homes, and economic well-being. It ignores scientific fact and common-sense observations to serve big political donors,” the senators said.

“This sham decision initially relied on a now thoroughly disgraced and abandoned ‘report’ by known climate deniers. Zeldin stuck to this charade anyway, undaunted by half a century of actual evidence, showing the fix was in from the beginning,” they continued.

Money and fossil fuels

The move outraged Democrats and climate activists when Zeldin first proposed it last summer. Climate activists say undoing the finding undercuts the federal government’s ability to address an issue critical to the United States and the entire world.

In a Tuesday floor speech, Schumer blasted the rollback as a giveaway to fossil fuel companies, leaders of which contributed to Trump’s 2024 campaign.

“Remember: In the spring of 2024, Donald Trump invited top oil executives to Mar-a-Lago and told them, if you raise me a billion dollars to get me elected, I will cut regulations so you can make more money,” Schumer said. “That devil’s bargain is now coming true. I never thought it would be this way in America, in this bald disgusting way that so hurts people’s health, but there it is.”

Democratic attorneys general and environmental groups are likely to sue over the rollback.

At least one lawsuit, from the Environmental Defense Fund, was promised Thursday afternoon.

“EDF will challenge this decision in court, where evidence matters, and keep working with everyone who wants to build a better, safer and more prosperous future,” Fred Krupp, EDF president, said in a statement Thursday. 

Washington state Attorney General Nick Brown, a Democrat, said last year he would “consider all options if EPA continues down this cynical path.”

Ashley Murray contributed to this report.