Supreme Court to decide fate of EPA mercury rule with billions at stake

The justices of the nation's highest court are weighing whether the Environmental Protection Agency should have considered potential compliance costs before proceeding with a rule that requires power plants to reduce their mercury emissions. In March, lawyers from the government and industry presented their sides to the Supreme Court, which could decide the matter in June, according to an article in Chemical & Engineering News (C&EN), the weekly newsmagazine of the American Chemical Society.

Glenn Hess, a senior correspondent at C&EN, notes that the EPA developed the requirement, called the Mercury & Air Toxics Standard, to curb the negative health effects of mercury and other air pollutants. The agency estimates that although the regulation will cost industry about $9.6 billion per year to fulfill, it will produce between $37 billion and $90 billion in health care savings annually. Opponents argued that these figures unfairly include "co-benefits" of reducing non-mercury pollutants. Controlling mercury would only amount to between $4 million and $6 million in savings a year, contend industry groups.

The justices were divided over whether the court should defer to EPA's interpretation of an ambiguous section of the Clean Air Act and allow the agency's final rule to stand. It appeared the decision would fall again to Justice Anthony Kennedy, often the swing vote.