Whether the D.C. Circuit's National Cement doctrine—under which a court must remand to the agency for a revised interpretation of a statute that the agency originally claimed to be unambiguous but which the court subsequently determines to be ambiguous, for the express purpose of then deferring to that revised interpretation after remand—is unconstitutional or otherwise impermissible.

Whether the doctrine of Chevron deference should be overruled or clarified.

Whether a truck or a truck maintenance yard that is not located at an extraction site, on an appurtenant road, or at a processing facility, is a "mine" under 30 U.S.C. § 802(h)(1).

Whether the National Cement doctrine of judicial remand for agency reinterpretation is unconstitutional and whether Chevron deference should be overruled or clarified