In early February 2016, the U.S. Supreme Court granted a stay of the Environmental Protection Agency’s (EPA) Clean Power Plan (CPP), freezing the rule’s implementation until final review by the courts. In response to petitions from more than two dozen states and many industry groups, this was the Supreme Court’s first stay of an administrative rule, reversing the D.C. Circuit’s earlier denial.

The CPP, linchpin of the Obama administration’s climate policy, is the most sweeping regulation in EPA’s history. The rule car- ries a $7.2 billion annual price tag. This is a conservative estimate, as total costs amount to over $30 billion. The rule has evoked the ire of constitutional scholars who view it as a fundamental violation of the U.S. Constitution’s provision on the separation of powers. The rule exceeds the legal authority that Congress delegated to the EPA through the Clean Air Act. In the CPP, the Obama-era EPA asserted the authority to federalize and overhaul the country’s electric power system, long a prerogative of state authority.