On April 2, the Supreme Court of the United States dropped a bombshell on U.S. climate policy: the Court ruled 5 to 4 in Massachusetts v. Environmental Protection Agency (EPA) that the EPA was now forced to regulate vehicular greenhouse gas emissions as specified in Section 202 of the Clean Air Act, a task the EPA had previously declined. While the EPA’s decision to decline was first upheld by the Court of Appeals for the D.C. Circuit, the Supreme Court disagreed, passing the ball back to the EPA.

The EPA is now under the gun to move forward with regulating vehicular greenhouse gas emissions, whether they do it voluntarily or are once again sued into doing so. Either way, it is a tricky mission: because greenhouse gases are unlike conventional pollutants, they can neither be blocked at the tailpipe nor minimized by pretreating or reformulating gasoline.

What are the implications and ramifications of the Supreme Court’s groundbreaking decision? Will it lead only to new automobile regulations, or will it lead to broader regulation of greenhouse gases under other sections of the Clean Air Act? What kind of regulations might the EPA issue in order to fulfill this new greenhouse gas control mission? A panel of legal scholars will discuss these and other questions as they review the Court’s decision.