On August 21, 2012, the U.S. Court of Appeals for the D.C. Circuit, in a 2-1 decision, vacated EPA's Cross-State Air Pollution Rule (CSAPR). This much-anticipated ruling strikes down one of the current Administration's most controversial and heavily litigated environmental rules.

Summary of the D.C. Circuit's Opinion -

The Clean Air Act (CAA) allows for rules to be promulgated to control upwind emissions, and also outlines a process to allow states to be the first to propose a plan to make these reductions; if the plans do not meet federal criteria, then the EPA may assume this responsibility. On August 8, 2011, EPA finalized CSAPR as its most recent attempt at a rule to set emissions caps for nitrogen oxides (NOx) and/or sulfur dioxide (SO2) in 28 states with the purpose of reducing impacts to downwind states' ability to comply with fineparticulate matter (PM2.5) and ozone standards.