Justice
Scalia authored the majority opinion, which Justices
Roberts and
Kennedy joined in full. The Court ruled that the EPA can regulate greenhouse emissions on power plants and other large stationary sources of pollution but that it overstepped its authority when it started to use the same regulations on smaller stationary sources like shopping centers, apartment buildings, and schools. In his opinion, Scalia noted that the
Clean Air Act imposes specific requirements on stationary sources of pollution that have the potential to emit 250 tons per year of "any air pollutant" or 100 tons per year for certain types of sources. Furthermore, the "any air pollutant" language in that section of the law specifically refers to regulated air pollutants, not greenhouse emissions. When the EPA attempted to apply the same standards to any source of greenhouse emissions, the Court objected that "would radically expand those programs, making them both unadministrable and unrecognizable to the Congress that designed them." Instead, the EPA adopted a different threshold for sources of greenhouse emissions, 100,000 tons per year. On the other hand, the Court ruled that the EPA could regulate the large sources of greenhouse emissions if they were already being regulated for emitting conventional pollutants. Scalia wrote that the "EPA may... continue to treat greenhouse gases as a 'pollutant subject to regulation'" under the provisions in the Act. Justice
Breyer wrote a concurring/dissenting opinion, joined by
Ginsburg,
Sotomayor, and
Kagan. Breyer argued that the EPA should have been allowed to interpret the "any air pollutant" language broadly to include greenhouse emissions as well: "I do not agree with the Court that the only way to avoid an absurd or otherwise impermissible result in these cases is to create an atextual greenhouse gas exception to the phrase 'any air pollutant.'"
Alito, joined by
Thomas, wrote a second concurring and dissenting opinion. They argued that the EPA should not be able to regulate the larger sources of greenhouse emissions by using those regulations: "The Clean Air Act was developed for use in regulating the emission of conventional pollutants and is simply not suited for use with respect to greenhouse gases." He cited two scenarios of incompatibility between greenhouses gases and normal pollutants, which eventually caused the EPA to declare that officials may disregard some provisions in the Act or to give authorities "a great deal of discretion." == References ==