In two decisions issued at the end of 2015, the Pennsylvania courts increased uncertainty regarding the breadth of the Arsenal Coal exception and status of pre-enforcement reviews. As a general rule, a regulated entity may only challenge regulations when the regulator imposes those regulations on the entity in a permit or enforcement action. In Pennsylvania, pre-enforcement review is not within the authority of the Environmental Hearing Board and the courts will only take on pre-enforcement reviews where the effect of the challenged regulations upon the industry regulated is direct and immediate, thereby establishing the justiciability of the challenge in advance of enforcement. The two opinions issued on Dec. 29, EQT Production v. Department of Environmental Protection, 15 MAP 2015 (Pa. Dec. 29, 2015) and PIOGA v. Department of Environmental Protection, 321 M.D. 2015 (Pa. Commw. Dec. 29, 2015), have the potential to expand the arsenal coal exception. If, in fact, the Arsenal Coal exception is broadened, it may simultaneously open a door to pre-enforcement challenges while shutting others on the grounds of preclusion, exhaustion, and finality.