Landmark Supreme Court Cases Will Help Clear the Air

The Supreme Court today made two landmark rulings today that will leave our air cleaner and our climate safer.

First, the Supreme Court unanimously ruled that Duke Energy, the largest utility in the country, could not escape clean air laws by only keeping hourly smokestack pollution in check. Duke Energy had argued that, even though annual emissions increased at some of its power plants, because hourly emissions did not increase, the company didn't have to install pollution controls. The Supreme Court commented that Duke Energy's arguments seemed "too far a stretch."

And they were. Duke Energy was arguing that it could increase its hours of operation and spew more pollution into the air, but not have to control its emissions. Their arguments violated a fundamental part of the Clean Air Act: Anytime a company modifies its power plant or other source of air pollution--including by increasing the hours of operation--and increases its overall annual pollution, that company needs to install up-to-date pollution controls to protect public health.

Second, the Supreme Court ruled in a 5-4 decision that the U.S. Environmental Protection Agency has the authority to regulate greenhouse gases under the Clean Air Act. The Clean Air Act gives EPA the authority to regulate air pollutants that endanger public health and welfare, like carbon dioxide and other greenhouse gases.

The EPA had taken the position that it didn't even have to review the health and welfare effects of greenhouse gases. Even though EPA has the discretion to decide which air pollutants to regulate, it still has to have a good reason for not regulating. The Supreme Court held that the EPA "offered no reasoned explanation" for refusing to assess how greenhouse gases affect public health and welfare.