A federal court has reinstated a major regulation to control emissions from coal-fired power plants but said the move was only a stopgap measure until EPA issues a replacement rule. On Dec. 23, 2008, the U.S. Court of Appeals for the District of Columbia Circuit modified its July 2008 decision overturning EPA's Clean Air Interstate Rule. That 2005 regulation was designed to reduce ground-level ozone and particle pollution in 28 eastern states. When it threw out the regulation last summer, the court deemed the rule fatally flawed and in violation of the Clean Air Act (C&EN, July 21, 2008, page 12). The court then instructed EPA to write a replacement regulation, a process that will take years. The July decision alarmed states, which were relying on the 2005 rule to help them meet federal air quality standards for ozone and particulate matter. Meanwhile, some coal-fired utilities began considering whether to operate the emissions-control equipment that they had installed to comply with the regulation, and other facilities canceled orders for pollution-control devices. States, EPA, and environmental groups asked the appeals court to reconsider its latest ruling. In its new decision, the full court agreed to let the 2005 regulation remain in effect until EPA issues a replacement rule. This means plant operators will have to carry through plans to install and operate pollution-control equipment. In a concurring opinion, Judge Judith W. Rogers explained, "The rule has become so intertwined with the regulatory scheme that [overturning it] would sacrifice clear benefits to public health and the environment while EPA fixes the rule."