On October 4, 2024, the U.S. Supreme Court declined requests from Republican-led states and industry groups to block two Environmental Protection Agency (EPA) rules regarding air pollutant emissions.

The Supreme Court upheld the Biden administration's new anti-pollution regulations focused on reducing mercury and methane emissions from fossil-fuel-fired power plants.

The mercury regulations, finalized in May, require compliance by July 2027, while the methane regulations aim for an 80% reduction in emissions between 2024 and 2038.

The EPA aims to combat climate change by limiting pollutants, with these regulations being part of a broader strategy to reduce emissions from fossil fuels.

The EPA estimates that power plants contribute over a quarter of the U.S. greenhouse gas emissions and are significant sources of toxic pollutants.

Opponents, including power and mining companies, argue that these regulations are costly and part of a broader agenda to phase out coal.

The refusal to intervene by the Supreme Court is seen as a positive step by environmental advocates, although it does not guarantee the EPA's success in future litigation.

The EPA defends the regulations as within its legal responsibilities aimed at protecting public health, emphasizing a balance between pollution reduction and reliable electricity delivery.

Mercury is recognized as a potent neurotoxin, while methane is a powerful greenhouse gas contributing to climate change.

Supporters of the new rules, including health organizations, argue that they will improve public health and mitigate climate impacts.

The National Resources Defense Council (NRDC) praised the Supreme Court's decision, highlighting the importance of maintaining environmental safeguards.

In a departure from previous cases, the Supreme Court advised challengers to pursue their claims in the U.S. Court of Appeals for the District of Columbia.