Massachusetts v. EPA (Apr. 2, 2007) was a 5-4 ruling by the U.S. Supreme Court that implicitly accepted theories of global warming and ordered the Environmental Protection Agency (EPA) either to begin regulating car emissions that "cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare," or to declare that greenhouse gases pose no threat.
At issue was an interpretation of the Clean Air Act which requires the EPA to issue regulations necessary to define standards to prevent air pollution. Congress passed a broad law seeking to prevent air pollution which may reasonably be anticipated to endanger public health or welfare. Congress left it to EPA to define different pollutants and to set emission standards. Until 2007, the EPA refused to conduct a rulemaking to determine how much greenhouse gas pollution should be allowed. Instead, the EPA was silent. On October 20, 1999, a group of 19 private organizations filed a rulemaking petition asking EPA to regulate “greenhouse gas emissions from new motor vehicles under §202 of the Clean Air Act. The EPA then sought public comment and data on the petition 15 months later. Before the close of the comment period, the White House sought “assistance in identifying the areas in the science of climate change where there are the greatest certainties and uncertainties” from the National Research Council, asking for a response “as soon as possible.” App. 213. The result was a 2001 report titled Climate Change: An Analysis of Some Key Questions (NRC Report), which concluded that “[g]reenhouse gases are accumulating in Earth’s atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise. Temperatures are, in fact, rising.”
On September 8, 2003, EPA entered an order denying the rulemaking petition. 68 Fed. Reg. 52922. The agency gave two reasons for its decision: (1) that contrary to the opinions of its former general counsels, the Clean Air Act does not authorize EPA to issue mandatory regulations to address global climate change, see id., at 52925–52929; and (2) that even if the agency had the authority to set greenhouse gas emission standards, it would be unwise to do so at this time. The Supreme Court summarized the EPA's position as, "In essence, EPA concluded that climate change was so important that unless Congress spoke with exacting specificity, it could not have meant the agency to address it." United States Court of Appeals for the District of Columbia Circuit voted 2-1 that the EPA had exercised its discretion correctly, and then the Supreme Court reversed in a decision forcing the hand of Congress as much as that of the EPA.
Until 2007, the Bush Administration has avoided political controversy by saying it lacks authority to regulate greenhouse gases, even though two prior EPA General Counsels had concluded that it had the power under the Clean Air Act. In this decision the Supreme Court has forced the hand of the Bush Administration to take a position one way or the other.
"We remain hopeful that the EPA will soon determine, as California has, that vehicle greenhouse gases must be reduced," Gov. Arnold Schwarzenegger declared in response.
California brought this lawsuit along with 11 other states, one U.S. territory, three cities and thirteen environmental groups. The lawsuit demanded that the EPA regulate carbon dioxide, methane, nitrous oxide and hydrofluorocarbons, all of which are considered to be "greenhouse gases." The lawsuit insisted that the Clean Air Act requires the EPA to limit pollutants that "may reasonably be anticipated to endanger public health or welfare."
Until now, the EPA has refused to regulate these gases because it claimed to lack authority, and because car exhaust has little effect on global greenhouse gases. But now the Supreme Court has held that the EPA does have authority, and must take a position.
Justice Kennedy provided the swing fifth vote to the liberal voting bloc of Justices Stevens (who wrote the decision), Souter, Ginsburg and Breyer. The conservative Justices Scalia, Thomas and Alito and the Chief Justice Roberts were in dissent.
The case prompted Congress to attempt to act. In 2009, the House passed a bill addressing greenhouse gas emissions, but the bill died in the Senate. In the absence of new legislation, the EPA under President Obama adopted climate change regulations and a Clean Power Plan. The Obama Administration also negotiated international agreements which obligated the United States to reach certain pollution goals in the future.