Congressional Research Service. May 1, 2012.

On April 2, 2007, the Supreme Court rendered one of its most important environmental decisions. In Massachusetts v. EPA, the Court held 5-4 that greenhouse gases (GHGs), widely viewed as contributing to climate change, constitute “air pollutants” as that phrase is used in the Clean Air Act (CAA). As a result, said the Court, the U.S. Environmental Protection Agency (EPA) had improperly denied a petition seeking CAA regulation of GHG emissions from new motor vehicles by saying the agency lacked authority over such emissions. This report offers a chronology of major federal agency actions, mainly by EPA, that involve GHGs or climate change and that occurred in the wake of Massachusetts v. EPA. Most of the listed actions trace directly or indirectly back to the decision.

http://www.fas.org/sgp/crs/misc/R41103.pdf [PDF format, 13 pages].