Massachusetts v. EPA is easily the Supreme Court’s most important environmental law decision in well over a decade. By a vote of 5–4, the Supreme Court set the Environmental Protection Agency (EPA) on a course to regulate greenhouse gas emissions and potentially remade much of administrative law. While the Supreme Court has been reluctant to authorize broad federal regulatory authority in other areas, the Massachusetts majority readily unearthed expansive yet untapped authority to control emissions of the most ubiquitous byproduct of modern industry. It is no wonder environmental advocates greeted the decision with cheer.
In their essay, Massachusetts v. EPA: Breaking New Ground on Issues Other than Global Warming, Professors Kathryn A. Watts and Amy J. Wildermuth have presented a thoughtful analysis of the Supreme Court’s handiwork in Massachusetts v. EPA. They are correct that the decision potentially paves new ground in administrative law, particularly with regard to state standing. The Court’s approach to review of agency decisions to decline rulemaking petitions is also potentially significant, but less ground-breaking than Watts and Wildermuth suggest. In the context of climate change policy, their assessment of the Court’s decision is farthest from the mark, however, for the Massachusetts majority did everything it could, given the posture of the case, to ensure federal regulation of greenhouse gases from motor vehicles and other emission sources. It is true, as a technical matter, that “the Court’s opinion did not order the EPA to regulate with respect to climate change.” Yet there should be little doubt that the Court’s judgment in the case gives the Agency little option but to regulate, and not just emissions from new motor vehicles. Unless the relevant provisions of the Clean Air Act are revised by Congress in new climate change legislation, Massachusetts v. EPA will mean greenhouse gas emission limits on industrial facilities and the likely regulation of carbon dioxide as a criteria air pollutant.