A coalition of states, utilities, energy producers, and other industry groups has brought a challenge in the U.S. Court of Appeals for the D.C. Circuit against the U.S. Environmental Protection Agency’s Clean Power Plan (CPP), which limits carbon dioxide emissions from the nation’s existing power plants pursuant to CAA §111(d). (A competing cohort of states, municipalities, companies, and environmental organizations has intervened in support of the rule.) As of this writing, merits briefing has yet to begin, but the petitioners offered a preview of their arguments in a set of motions to stay the CPP pending resolution of their suit. In support of the stay requests, the petitioners filed dozens of declarations from state government officials and industry representatives, many of which made exaggerated claims regarding the “unprecedented” nature of the CPP. In this Comment, the authors highlight a wide variety of regulations from the CAA’s 45-year history that provide substantial precedent for the flexible design of the CPP.