We've reported previously on U.S. EPA’s final air emission rules for E&P facilities, implementing New Source Performance Standards (“NSPS”) for volatile organic compounds (“VOC”) and sulfur dioxide (“SO2”), and National Emissions Standards for Hazardous Air Pollutants (“NESHAP”).  Nine separate petitions were filed recently with the DC Circuit Court of Appeals challenging those rules for the oil and natural gas sector (consolidated for review in American Petroleum Institute v. Environmental Protection Agency, Case No. 12-1405).