EPA's Authority To Regulate GHG Emissions From Power Plants After UARG

The United States Supreme Court's recent decision in UARG v. EPA offers insight as to how future courts will evaluate the authority of the Environmental Protection Agency ("EPA") under the Clean Air Act ("CAA") to regulate greenhouse gas ("GHG") emissions from power plants and other stationary sources. In UARG, EPA had interpreted the CAA, through the Tailoring Rule, as requiring Prevention of Significant Deterioration ("PSD") and Title V permitting on the sole basis of a source's potential to emit GHGs.

The Supreme Court rejected this interpretation, holding that Congress must "speak clearly if it wishes to assign to an agency decisions of 'vast economic and political significance.'" Thus, the takeaway from UARG is that EPA rulemaking—especially rulemaking that would bring about an "enormous and transformative expansion in EPA's regulatory authority"—must be grounded in and judged against the statutory text of the CAA.