by Lisa Heinzerling, Justice William J. Brennan, Jr., Professor of Law, Georgetown University Law Center
The Supreme Court has split 5-4 in three decisions involving the regulation of greenhouse gases. The federal government's program to reduce greenhouse gas emissions was set in motion by the Court's 5-4 ruling in Massachusetts v. EPA. Another 5-4 decision in Utility Air Regulatory Group v. EPA rejected EPA's application of permitting requirements to stationary sources based on their greenhouse gas emissions alone, and embraced an interpretive principle that would disfavor ambitious agency interpretations of longstanding statutes. In a third 5-4 ruling, West Virginia v. EPA, the Justices voted to stay EPA's regulation limiting greenhouse gases from existing power plants.
With thin and shifting majorities like these, it is quite clear that one Justice may determine the fate of the country's regulatory programs for climate change.
The federal government began to regulate greenhouse gas emissions only after losing a case in the Supreme Court. In Massachusetts v. EPA, the Supreme Court rejected the reasons EPA had given for refusing to regulate greenhouse gases under the Clean Air Act. In response to a citizen petition asking the agency to regulate greenhouse gas emissions from motor vehicles under the Clean Air Act, EPA had argued that it simply had no authority to regulate these pollutants under the Act. The Supreme Court disagreed by a vote of 5-4 and held that the agency does have authority to regulate greenhouse gases because greenhouse gases are "air pollutants" within the meaning of the Clean Air Act. The Court observed that the broad language of the Clean Air Act reflected "an intentional effort to confer the flexibility necessary to forestall . . . obsolescence" in the presence of "changing circumstances and scientific developments."
By the same margin, the Court also rejected EPA's policy-based justifications for refusing to regulate greenhouse gases. The Court ruled that EPA erred by citing a "laundry list" of reasons why it preferred not to regulate, rather than grounding its decision in the statutory criterion of endangerment of public health and welfare. Even if the agency found the science of climate change uncertain, the Court said, the agency could not refuse to regulate greenhouse gases unless the science was so profoundly uncertain that the agency could not even form a judgment as to whether greenhouse gases were endangering public health or welfare. "The statutory question," the Court explained, "is whether sufficient information exists to make an endangerment finding."