As reported by Platts, on October 21st the D.C. Circuit Court of Appeals asked whether the parties involved in the lawsuits that led to vacatur of the Clean Air Interstate Rule (CAIR) want the entire rule to be thrown out or to be kept in place until U.S. EPA revises the rule. 

The US Court of Appeals for the District of Columbia Circuit on Tuesday
ordered petitioners — which include utilities Duke Energy and Entergy — to
respond within 15 days to its inquiry.

It is a move CAIR supporters see as a hopeful sign.

"We see it as a sign that [the court is] working through the reasoning of
our position and, hopefully, will make the right decision" and keep CAIR in
place, said EPA spokesman Jonathan Shradar.

Asking the petitioners whether they want the entire rule thrown out or a
stay of the court mandate indicates the DC Circuit is "taking our petition
seriously," he added.

If the DC Circuit stays its mandate, CAIR could stay in place until EPA
puts in place a revised rule.

This puts the Utilities in an interesting position.  EPA has indicated that CAIR would need a significant rewrite which would include weakening protections that were provided to the Utilities under the original rule.  The weakening would likely include removal of the shield that EPA constructed that protected the Utilities from claims that interstate transport of pollution was not adequately addressed by CAIR.

Given the 15 day deadline, the briefs should have been filed.  It will be very interesting to how the Utilities like to gamble.  Would they prefer the rule to be thrown out and take their chances a new program is developed that is stronger?  Would the prefer maintaining at least the first phase of CAIR to give them some certainty in the allowance markets and be able to plan for new pollution controls?