The U.S. Court of Appeals for the Fifth Circuit has stayed a lawsuit, Sierra Club v. EPA, brought by a coalition of environmental groups concerning the U.S. Environmental Protection Agency’s (EPA) approval of two revisions to the Texas State Implementation Plan (SIP). This stay is to allow the U.S. Court of Appeals for the D.C. Circuit to decide whether to hear an identical petition for review. The petitioners sued EPA in both courts but argue that the case belongs in the D.C. Circuit because petitioners contend that the EPA decisions at issue concern federal air standards and are nationally applicable. EPA and respondent-intervenors, led by the State of Texas, argue that the lawsuit is of only regional significance because the case pertains to EPA actions on plans for metropolitan Houston and Dallas and therefore belongs in the Fifth Circuit. On February 14 and April 6, EPA approved the Texas SIP revisions, finding the Houston and Dallas areas had each sufficiently demonstrated that the areas met the redesignation criteria for the 1979 1-hour and the 1997 8-hour national ambient air quality standards (NAAQS) for ozone, two standards EPA has since revoked through new ozone NAAQS in 2008 and 2015. As part of its approvals, EPA terminated the “anti-backsliding” measures associated with the revoked NAAQS, an action the petitioners challenge.