On February 28 and 29, 2012, the U.S. Court of Appeals for the District of Columbia (D.C.) Circuit heard oral argument in a series of closely watched lawsuits challenging regulations issued by the U.S. Environmental Protection Agency (EPA) to regulate greenhouse gas (GHG) emissions from automobiles and manufacturing facilities under the Clean Air Act (CAA). Many observers consider the suite of GHG lawsuits, brought by industry groups and state petitioners, among the most significant in CAA and  administrative law in the last 30 years. This is because the D.C. Circuit’s decision will address the proper scope of EPA’s prevention of significant deterioration (PSD) program and of rarely invoked judicial doctrines of last resort like “absurd results” and “administrative necessity.” Moreover, the court’s decision will address those issues
in the context of GHG emissions, one of the most politically and scientifically charged issues of our times.