Yesterday, the Court of Appeals for the 4th Circuit reversed a District Court decision and rejected the lawsuit by Murray Energy 
which argued that EPA had a non-discretionary duty under § 321(a) of the Clean Air Act to:
conduct continuing evaluations of potential loss or shifts of employment which may result from the administration or enforcement of the provision of this chapter and applicable implementation plans, including where appropriate, investigating threatened plant closures or reductions in employment allegedly resulting from such administration or enforcement.
The Court concluded that this language “does not impose on the EPA a specific and discrete duty amenable to” judicial review. As the Court noted:
Section 321(a) calls for evaluations without, for the most part, specifying guidelines and procedures relevant to those evaluations. Furthermore, Section 321(a) establishes no start-dates, deadlines, or any other time-related instructions to guide the EPA’s continuous evaluation efforts.
I’m not surprised by the outcome. Notwithstanding my usual reluctance to speculate, I did go a short way out on a limb and state that the District Court “probably got this one wrong.” The more interesting question is why the current administration pursued the appeal. It says something about the havoc that this would have caused that even Scott Pruitt did not want to deal with judicial review over a continuing obligation to evaluate potential job losses resulting from EPA regulations.
This might be interpreted as Pruitt seeking more opportunities to perform unconstrained reviews when and how he wants to. Not inconsistent with his earlier action to give himself more case-by-case Superfund review opportunities.