The Clean Air Act’s good neighbor provision prohibits upwind states from emitting air pollutants in amounts that will “contribute significantly to nonattainment” of a national ambient air quality standard in a downwind state. On Wednesday, the D.C. Circuit Court of Appeals held that, while upwind states have to be good neighbors, EPA cannot force them to be extraordinarily super-special neighbors. Just good enough will have to do.
Following the Supreme Court’s decision affirming EPA’s Transport Rule against facial challenges in