"The standards are a notable environmental accomplishment for President Barack Obama and a blow to the coal industry, which is the biggest source of mercury emissions in the U.S., according to the Environmental Protection Agency," write Amy Harder and Brent Kendal about the ruling by the U.S. Court of Appeals for the District of Columbia Circuit. The EPA standards were challenged "by more than 20 states with utilities that depend heavily on coal for energy production."
The court's majority ruled the EPA acted reasonably in issuing the rules, rejecting arguments that the agency should have considered the costs of its regulations before moving forward. A dissenting judge, Brett Kavanaugh, warned the regulations would cost utilities more than $9 billion a year.
According to the EPA webpage on mercury, heretofore "there have been no federal standards that require power plants to limit their emissions of toxic air pollutants like mercury, arsenic and metals - despite the availability of proven control technologies, and the more than 20 years since the 1990 Clean Air Act Amendments passed."
That would be scrubber technology that should be able to reduce mercury emission, "a neurotoxin the EPA says is known to cause brain damage and other health problems, particularly in developing fetuses and young children," by at least 90%."
These new regulations, which precede President Obama's proposed regulations on greenhouse gas emissions by a good 20 years, along with much-reduced prices in natural gas, led to utilities retiring coal-burning generators and replacing them with natural gas generators.
As for an appeal to the Supreme Court, "Michigan Attorney General Bill Schuette, one of the states in the lawsuit," indicated through a spokesperson: "We are reviewing the opinion and considering our options in consultation with other states."