On December 30, 2011, the United States Court of Appeals for the District of Columbia issued an order staying the Cross-State Air Pollution Rule (CSAPR) pending the resolution of an appeal of the rule. Several companies, industry groups and states appealed CSAPR after it was promulgated in July 2011. The petitioners in the appeals, which have been consolidated, filed motions asking the court to stay the rule pending review. In their motions, petitioners listed unrealistic compliance deadlines, reliability concerns and federalism concerns as among the reasons warranting a stay. The court issued a two page per curiam order granting the petitioners' stay motions, noting that petitioners "satisfied the standards required for a stay pending court review," but adding no further reasoning for its decision. Absent the stay, the rule would have become effective on January 1, 2012.

The court's order also states that the United States Environmental Protection Agency is expected to continue administering the Clean Air Interstate Rule (CAIR) pending resolution of the CSAPR appeals. CAIR was supposed to be implemented through 2011 compliance periods and then replaced by CSAPR. The court's order suggests that CAIR 2012 compliance schedules will come back into effect during the pendency of the CSAPR stay.

While there is no way to know exactly when the court will issue a final decision regarding the CSAPR appeals and, therefore, exactly how long the stay will remain in effect, the court did order the parties to submit proposed briefing schedules that would allow the appeals to be heard by April 2012.