Attorney General Brown Joins Lawsuit Challenging Trump Administration Rule That Weakens Regulation of Highly Potent Greenhouse Gas

Published: 7/21/2026


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BALTIMORE, MD – Attorney General Anthony G. Brown today joined a coalition of attorneys general in filing a lawsuit against the U.S. Environmental Protection Agency (EPA), challenging its rule that would weaken regulations designed to phase out the use of hydrofluorocarbons (HFCs) in commercial equipment.  

HFCs are chemicals used for refrigeration and cooling that have a global warming potential up to 10,000 times more than carbon dioxide, and they are among the fastest growing source of greenhouse gas emissions both in the United States and around the world. The rule rolls back some of the existing deadlines for industry to move from using HFCs as refrigerant gases to refrigerants with less greenhouse effect, known as Global Warming Potential (GWP). This undermines the EPA’s current regulations under the American Innovation and Manufacturing Act of 2020 (AIM Act), which are designed to phase out HFCs by approximately 85% by 2036. 

In the petition filed today in the U.S. Court of Appeals for the District of Columbia Circuit, Attorney General Brown and the coalition ask the Court to review the EPA’s new rule because it is contrary to law and the EPA fails to justify its change in position.  

“Every summer, Marylanders hear the same report: this is the hottest year on record. That trend will only accelerate if refrigerant gases like these go unchecked,” said Attorney General Brown. “We are challenging the EPA’s rule because our climate’s future depends on protections against dangerous greenhouse gases.”  

HFCs are widely used in commercial, residential, and mobile cooling systems, such as air conditioning and refrigeration. Once deemed a safer alternative for the environment relative to ozone-depleting substances (chlorofluorocarbons, or CFCs), which damage the earth’s ozone layer, HFCs were later discovered to pose a major threat to the climate. With GWPs hundreds to thousands of times higher than carbon dioxide over a hundred-year period, HFCs have been projected to contribute up to 0.5 degrees Celsius (about 0.9 degrees Fahrenheit) to global surface warming by 2100 if they are not controlled. Because of this extreme potency, HFCs’ increasing share of emissions, and their relatively short lifespan in the atmosphere, reducing consumption and production of HFCs is particularly important for addressing climate change.  

In December 2020, President Trump signed the Bipartisan AIM Act into law. The AIM Act provides a framework through which the United States will phase out the production and consumption of HFCs by about 85% by 2036. That law limits production and imports of HFCs in the U.S. to declining amounts of historic baseline levels – 60 percent today, declining to 30 percent in 2029, and 15 percent in 2036. The law requires the EPA to help industry transition to a lower supply of these gases by setting limits for sectors with more readily available alternatives to protect costs and supply for those sectors that will take longer to transition. That’s what the prior Technology Transitions rule did: it required specific sectors that use refrigerants to, when installing new equipment, install equipment that uses gases with lower GWP. For example, under the prior Technology Transitions rule, new remote condensing units – typically used to refrigerate food by retailers like supermarkets, bakeries, and conveniences stores – were limited to using refrigerants with 150 to 300 GWP, depending on the system, starting January 1, 2026. With the EPA’s rollback, new remote condensing units could use refrigerants with 10 times greater global warming potential (up to 1,400 GWP) until January 1, 2032.   

If allowed to move forward, the rule will increase HFC emissions, accelerating the damage already threatening our planet from climate change. Further, by undermining the parallel reduction in HFC supply and demand, the rule threatens to cause shortages and price spikes in the HFC market that could be passed from retailers to consumers.  

Joining Attorney General Brown in filing the lawsuit are the attorneys general of California, Washington, Colorado, Delaware, Hawai‘i, Illinois, Maine, Michigan, Minnesota, Nevada, New Jersey, New York, Oregon, Rhode Island, Vermont, Wisconsin, the Commonwealth of Massachusetts, the District of Columbia, and the City of New York.  

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