On March 20 2018 a three-judge panel in the US District Court for the District of Columbia unanimously upheld a portion of the Environmental Protection Agency's (EPA's) regional haze rule that allows states to treat compliance with the Cross-State Air Pollution Rule as better-than-best available retrofit technology (BART) for states participating in the Cross-State Air Pollution Rule. Challenges to the EPA's interpretation of the rule came from two sides: environmental non-governmental organisations (ENGOs) and power companies joined by trade groups.

The ENGOs asserted that the EPA had erred by comparing the wrong averages when it evaluated BART emissions modelling against Cross-State Air Pollution Rule emissions. The court pointed to a previous opinion in which it had upheld the Clean Air Interstate Rule (the predecessor to the Cross-State Air Pollution Rule) and found that "nothing in the Clean Air Act's 'reasonable progress' language requires at least as much improvement at each and every individual area as BART itself would achieve". Industry, on the other hand, argued that when the EPA replaced the Clean Air Act with the Cross-State Air Pollution Rule, it had effectively disapproved several state implementation plans that relied on the Clean Air Act as the operative better-than-BART standard. The court rejected these arguments, stating that the Clean Air Act was a defunct standard that could not be resurrected, nor form the basis for state implementation plan approval.

For further information on this topic please contact Samuel B Boxerman or Jim Wedeking at Sidley Austin LLP by telephone (+1 202 736 8000) or email ([email protected] or [email protected]). The Sidley Austin LLP website can be accessed at www.sidley.com.