En banc panel for Clean Power Plan expands (creating potential for a tie vote)

On Thursday, in a brief order, the U.S. Court of Appeals for the D.C. Circuit announced that all but one of the court's active judges (Merrick Garland) will be participating in the en banc review of the Environmental Protection Agency's Clean Power Plan regulations. What this means is that the case will now be heard by 10 judges instead of nine.

Why did this happen? Presumably because whatever conflict had required Judge Cornelia Pillard to recuse herself has been eliminated, but the court did not say.

One interesting consequence of this change is that there is now an even number of judges hearing the case, and this creates the possibility (however remote) of a 5-5 split. When the Supreme Court splits evenly, the judgment of the lower court is upheld without opinion (and without a precedential holding). The same thing happens if the D.C. Circuit splits evenly with regard to a trial court judgment.

Does it follow that a 5-5 vote is a win for the EPA? I would assume so—without a majority, the court lacks the power to vacate or remand the rule being challenged—but I do not know of a specific rule or precedent that speaks to this precise scenario.

Here's some background on the Clean Power Plan, the Supreme Court's unexpected stay of the EPA rules and the D.C. Circuit's initial decision to hear the case en banc.