On Friday, the Supreme Court allowed the Environmental Protection Agency (EPA) to continue enforcing new rules to reduce harmful emissions from coal-fired power plants, including mercury and other toxic metals. The decision marks a significant moment in the ongoing battle over environmental regulations.
This ruling is part of a larger debate on the limits of federal regulatory power. The EPA's Mercury and Air Toxics Standards (MATS), introduced in 2012, have been a flashpoint for environmental and industry groups. The 2023 updates to MATS, the subject of this case, impose stricter standards on emissions from coal plants and represent one of three major regulations issued by the Biden administration targeting pollution from fossil fuels.
The MATS rule, first implemented to address hazardous pollutants like mercury and arsenic emissions, saw adjustments in May 2023. The EPA justified the change by citing technological advancements that make more stringent limits feasible. These adjustments took effect in July, giving plants three years to comply. The EPA argued that 90% of the coal-fired plants can meet these new standards with little to no additional cost. Only two plants in Montana were found to require substantial upgrades to meet the revised limits.
Opposition came swiftly. Twenty-three states, power plants, and energy industry groups challenged the rule, arguing that compliance costs could destabilize the nation’s power grid without yielding significant public health benefits.
They claimed the EPA failed to quantify any meaningful health or environmental improvements from the mandated emission reductions. These states warned that the rule’s implementation could result in power plant closures and rising electricity costs. The Supreme Court, however, declined to block the rule, allowing it to remain in effect while the legal challenge continues.
This is not the first time the Supreme Court has dealt with the EPA’s authority under the Clean Air Act. In 2015, the Court ruled that the EPA failed to properly consider the costs of regulating emissions under MATS, leading to a reevaluation that ultimately upheld the rule as "appropriate and necessary" in 2023. The Biden administration has vigorously defended these regulations, asserting that nearly all coal plants can meet the tightened standards without significant investments, and no plants are expected to shut down due to the rule.
The decision follows a string of recent Supreme Court rulings that have limited the EPA’s ability to regulate air and water pollution. In June 2022, the Court ruled that the EPA did not have the authority to regulate carbon dioxide emissions through the Clean Power Plan, and just months later, it blocked the agency’s “good neighbor” rule designed to reduce air pollution across state lines.
The ruling also highlights other significant environmental regulations currently under scrutiny. The Supreme Court is expected to weigh in on another critical rule to curb oil and gas industry methane emissions. The methane rule, part of the Biden administration’s broader climate strategy, sets new requirements on existing wells and aims to reduce routine natural gas flaring, a potent contributor to climate change. Industry groups have decried the rule as overly stringent and unachievable.
The Supreme Court’s decision to leave the EPA’s mercury rule intact underscores the complex and often contentious relationship between federal regulatory authority, state governments, and the energy industry. As legal battles over environmental regulations unfold, the balance between protecting public health and ensuring economic stability remains at the forefront of the nation’s environmental policy debates. With key decisions on methane and greenhouse gas emissions still pending, the Court’s rulings will play a crucial role in shaping the future of U.S. environmental policy.
