Folded into the text of the climate, health care and tax bill that became law last week is language that may buttress a 2007 Supreme Court precedent underpinning EPA’s authority to regulate greenhouse gases under the Clean Air Act.

The measure signed into law by President Joe Biden on Aug. 16 included multiple amendments to the foundational environmental law first passed in 1970. Senate Environment and Public Works Chairman Thomas R. Carper, D-Del., said they were “the most significant changes since 1990.”

They label six types of greenhouse gases — carbon dioxide, hydrofluorocarbons, methane, nitrous oxide, perfluorocarbons and sulfur hexafluoride — as air pollutants under the act. While the Supreme Court has ruled the EPA has authority to regulate these gases as air pollutants, that authority to date has not been reflected in statutes.

In 2007 the Supreme Court ruled 5-4 in Massachusetts v. EPA that the agency does have the authority under the Clean Air Act to regulate carbon dioxide and other heat-trapping gases.

At the time, the George W. Bush administration argued that whether or not to regulate greenhouse gases was a choice within its discretion. But in his opinion for the majority, then-Justice John Paul Stevens said the “statute is unambiguous.”

That led to an “endangerment finding” issued under President Barack Obama in 2009, in which the EPA determined that greenhouse gases threaten the well-being and health of current and future generations.

Following the subsequent rightward shift of the court, environmentalist lawyers, climate groups and Democratic lawmakers feared that the Trump administration might try to challenge one or both of those legal pillars.

Conservative court

While there are three justices who dissented in Massachusetts v. EPA currently sitting on the court — Chief Justice John Roberts and justices Clarence Thomas and Samuel Alito — every judge who ruled in the majority is either dead or has retired from the bench, and the Senate solidified the court’s conservative majority with the confirmation of President Donald Trump’s nominees.

The court has also taken a more skeptical stance toward the EPA’s ability to broadly regulate emissions, including its June ruling in West Virginia v. EPA. Joined by conservative and industry trade groups and other Republican-led states, West Virginia and coal-mining companies had brought a challenge against the agency’s authority to regulate greenhouse gases under a federal law using a system to cap emissions because Congress had not specifically authorized it to do so.

Writing for the majority in the West Virginia case, Roberts said “it is not plausible” that Congress gave the EPA “the authority to adopt” a strategy to lower emissions by setting caps on how much pollution can be released.

“A decision of such magnitude and consequence rests with Congress itself, or an agency acting pursuant to a clear delegation from that representative body,” Roberts said.

While West Virginia Attorney General Patrick Morrisey and staffers from both parties agreed that the law signed by Biden does not override the ruling in West Virginia v. EPA, a case that centered on the methods by which the agency can regulate emissions, it may more explicitly establish the agency’s authority to do so.

David Doniger, senior strategic director of the climate and clean energy program at the Natural Resources Defense Council, said that the language in the new law “will make it much harder” for groups pushing to erode Massachusetts v. EPA, or for any group to argue that the agency cannot regulate greenhouse gas emissions.

Republicans had initially expressed concerns that the reconciliation law included broader regulatory language, but this provision was ultimately stripped after rulings by the Senate parliamentarian and negotiations with Democrats.

Staff for the Republicans on the Senate Environment and Public Works Committee said that because the definition outlining greenhouse gases was included only in the amendments and not in the Clean Air Act’s overarching definition section, there is a distinction legally.

Still, the committee’s top Republican, Shelly Moore Capito of West Virginia, said the new law “contains dozens of harmful policies.”

Doniger said that as the EPA faces future battles over the impact its standards may have, these amendments will give the agency congressional language to cite.

“The new law’s direction to regulate and its incentives that reduce costs for regulated entities and their customers will help us in those fights but does not definitively resolve those future questions of design and stringency,” Doniger said.