Photo: Creative Commons/Flickr

In a major decision today, the U.S. Supreme Court ruled the Environmental Protection Agency did not properly consider costs when it created a rule to limit mercury emissions from power plants.

Finalized in 2012, the Mercury and Air Toxics Standard is one of the Obama administration’s most significant efforts to combat harmful air pollution and protect public health. Mercury is a neurotoxin that can bypass the body’s placental and blood-brain barriers, threatening cognitive development and the nervous system.

The rule, which also targets pollutants such as arsenic, chromium and hydrochloric acid gas is expected to prevent 11,000 premature deaths, 4,700 heart attacks and 130,000 asthma attacks each year.

While difficult to quantify, the rule’s health benefits would well exceed the estimated $9.6 billion cost in annual compliance costs. In fact, a formal analysis found the quantifiable benefits of the rule could reach $80 billion each year — as much as $9 for every dollar spent.

Still, industry groups and several states argue the EPA did not adequately consider costs when determining whether regulating mercury under the Clean Air Act is “appropriate and necessary.”

Last year, the U.S. Court of Appeals for the District of Columbia Circuit sided with the EPA, leading the challengers to ask the Supreme Court to hear the case. Today’s 5-4 ruling remands the case back to the D.C. Circuit Court, which could order the EPA to reconsider the costs of compliance or to craft a new plan to regulate mercury altogether.

A statement from Appalachian Voices Campaign Director Kate Rooth:

Today’s Supreme Court ruling is a disappointing setback; for far too long the costs of unregulated pollution to human health and the environment have not been adequately weighed in determining our energy future. The Mercury and Air Toxics Standard is a critical component of the Obama administration’s effort to curb pollution from power plants. This rule has already resulted in many of the oldest and dirtiest coal plants being retired or updated, and it is critical that these safeguards remain in place in order to protect communities and future generations from mercury and other toxic air pollution.

The Supreme Court decision still provides a clear path forward for the EPA to limit dangerous mercury and other toxic pollutants in our air. We are confident that the agency will be able to respond to the court’s ruling by demonstrating that the health costs of continued power plant pollution greatly outweigh the costs of the rule itself.