On May 20, 2011, eighty parties representing a cross-section of American business filed their opening brief in the U.S. Court of Appeals for the D.C. Circuit (“D.C. Circuit” or the “Court”) challenging EPA’s finding that greenhouse gases (“GHGs”) emitted by new motor vehicles endanger the public health and welfare by contributing to climate change.  A group of states filed separate briefs challenging that finding as well.

EPA’s endangerment finding triggered regulation by EPA of GHG emissions from new motor vehicles beginning with model year 2012 and also regulation of GHG emissions from stationary sources under the “PSD” and “Title V” air quality permit programs beginning on January 2, 2011.  EPA issued two further rules, known as the “Timing Rule” and “Tailoring Rule,” under which PSD and Title V regulation was implemented.

Briefs challenging the motor vehicle rule are due June 3 and briefs challenging the Timing and Tailoring Rules are due June 20.  Briefing in all of these cases, which the Court will hear before a single panel, will continue throughout the year, with a final decision not expected until later 2012 or into 2013.