On August 30, 2007, the U.S. District Court for the Southern District of Mississippi granted defendants’ motion to dismiss, finding that plaintiffs’ nuisance claims raised a non-justiciable political question and that plaintiffs did not adequately allege the "causation" element required for standing, as defined by the Supreme Court in Lujan v. Defenders of Wildlife, 504 U.S. 555 (1992).  2007 WL 6942285 (S.D.Miss. Aug. 30, 2007) (NO. 1:05-CV-436 LG-RHW).  On appeal to the U.S. Court of Appeals for the Fifth Circuit, a three-judge panel issued an opinion reversing the lower court's decision. The appellate court panel held that plaintiffs had standing, under both state and federal law, to bring their common law claims. The court further held that the case did not raise a non-justiciable political question. 585 F.3d 855 (5th Cir. 2009).

Defendants asked for a rehearing en banc, i.e., by all sixteen of the judges sitting in the Fifth Circuit. Seven judges disqualified themselves from the decision on whether to grant rehearing. The remaining nine judges voted and decided to grant a rehearing en banc, which vacated the three-judge panel’s opinion.  After the decision to grant a rehearing en banc, one of the remaining nine judges recused herself. This left only eight judges sitting en banc, which a majority of the remaining judges determined was less than the quorum needed to transact judicial business. In response, over the dissent of three of the remaining judges, a majority of the  eight judges decided that, because there was no quorum, there could be no opinion or judgment from the Fifth Circuit in the case and directed a dismissal of the appeal. Because the Fifth Circuit’s three-judge panel opinion had been vacated when there had been a quorum of the court, there was no longer any decision in effect reversing the district court’s decision.  607 F.3d 1049 (5th Cir. 2010). Absent direction otherwise from the U.S. Supreme Court, plaintiffs' case was over.

On late August 2010, plaintiffs filed a petition seeking a writ of mandamus with the U.S. Supreme Court.  In re Comer, et al., No. 10-294 (docketed Aug. 30, 2010).  Without asking the Supreme Court to address the merits of their suit, plaintiffs asked the Supreme Court to require the Fifth Circuit to address the merits of their appeal in that lower court.  After full briefing of the parties on the writ of mandamus, the Supreme Court held a conference considering the petition on Friday, January 7, 2011.  On Monday, January 10, 2011, the Supreme Court announced that the petition for a writ of mandamus would not be granted, thus ending plaintiffs' lawsuit and precluding any recovery by plaintiffs on their claims.

Because the Supreme Court did not issue a decision on the merits in Comer, the Supreme Court's decision in American Electric Power Co. v. Connecticut, which is before the Court on a writ of certiorari from the Court of Appeals for the Second Circuit, 582 F.3d 309 (2d Cir. 2009), will be the first opportunity for the Court to directly address the issue of whether parties can pursue common law claims in federal court to address GHG emissions.