On January 20, 2014, the Utility Air Regulatory Group (UARG) filed a Petition for Review of EPA’s recently finalized amendments to the Mercury and Air Toxics Standards (MATS) startup and shutdown work practice standards in the U.S. Court of Appeals for the D.C. Circuit. The petition does not state the basis for the suit, but it is expected that UARG will challenge provisions in the rule that differ from EPA’s November 2012 and June 2013 proposals, including the alternate definition of startup, the requirement to use clean fuels to the maximum extent possible during startup, and the requirements for engagement and disengagement of air pollution control devices during startup and shutdown.

It is unlikely that the D.C. Circuit will rule on UARG’s petition before the Supreme Court renders its decision in Michigan v. EPA, which is expected in June 2015.