When it comes to federal regulation, the D.C. Circuit is arguably the most important court in the nation. Not only does it see more cases challenging government rulemaking, it throws out those rules regularly -- at a rate significantly higher than any other circuit.
The EPA is no stranger to the less-than-deferential D.C. Circuit, with two recent EPA cases making the news over the past weeks. Last Wednesday, SCOTUS heard oral arguments over the EPA's mercury and air toxics rules, which the D.C. Circuit upheld and several states say improperly ignore costs. The agency was also recently instructed by the circuit to revisit its dust corrosivity standards after an EPA scientist sued, saying that the standards were too lax and failed to protect 9/11 first responders.