"Federal appeals are heard by three-judge panels chosen at random. Under very rare circumstances, once a panel has decided a case, the full court can grant the losing party’s request to rehear the case en banc, meaning all of the active-service judges will rehear the case together.
In this case, the Richmond, VA-based court voted on its own initiative to make the initial hearing of the case an en banc hearing. Such a procedural move is exceedingly unusual, almost unheard-of.
Barack Obama had an unusually high number of appointments to the Fourth Circuit because Senate Democrats blocked many of George W. Bush’s nominees to that appellate court. As a consequence, the 15-judge appeals court is comprised of nine liberal judges, three moderates, and three conservatives."