On July 11, 2008 the U.S. Court of Appeals for the D.C. Circuit found "more than several fatal flaws" in EPA's Clean Air Interstate Rule (CAIR) and vacated the rule in its entirety. EPA subsequently filed a petition for rehearing or a remand of the case without vacatur. After receiving and reviewing responses from the involved parties, the court granted EPA's petition in a December 23 opinion and remanded the rule to EPA without vacatur. The court's reasoning was that vacatur of the rule "would at least temporarily defeat ... the enhanced protection of the environmental values covered by [the EPA rule at issue]."

The court stated that "allowing CAIR to remain in effect until it is replaced by a rule consistent with our opinion would at least temporarily preserve the environmental values covered by CAIR." Although some of the petitioners suggested that the court impose a definitive deadline by which EPA must correct CAIR's fatal flaws, the court chose not to do so. However, the court warned that "... we do not intend to grant an indefinite stay of the effectiveness of this court's decision."

Wisconsin has issued a statement of scope for proposed revisions to NR 433 - Protection of Visibility by Application of Best Available Retrofit Technology (BART). The statement of scope outlines the objective of the proposed rule changes to include additional time and flexibility for compliance with BART for electric generating units which are now BART affected sources as a result of the CAIR vacatur. Wisconsin is considering the time and flexibility for these units due to the size and complexity of SO2 and NOx control equipment.

Link to WDNR Rulemaking Statement of Scope