Two Landmark Interpretations of the Clean Air Act
The most recent U.S. Supreme Court term is notable for two landmark interpretations of the Clean Air Act (CAA). In Massachusetts vs. EPA (U.S., No. 05-1120, 4/2/07), the court held that greenhouse gases (GHGs) are air pollutants subject to regulation under the CAA, overruling an interpretation by the Bush administration. In Environmental Defense vs. Duke Energy Corp. (U.S., No. 05-848, 4/2/07), the court held that when renovation of an industrial facility results in an increase in annual emissions, modern emission controls must be installed, even if the hourly rate of emissions does not increase. This article traces the history of these cases and considers their implications.