The Supreme Court has struck down an attempt by the White House to relax New Source Review (NSR) rules. In early May, the court refused to hear the administration’s appeal of a lower court ruling that struck down changes to the Clean Air Act.

According to the rule, which was adopted by the EPA in 2003 but never took effect, modern antipollution controls would have to be installed only if plant upgrades cost more than 20 percent of the replacement cost of the plant. Utilities, oil refineries and other industries sought to be able to upgrade or modify their facilities without triggering NSR provisions that would require additional upgrades, and costing billions of dollars more. Environmental groups and 14 states joined to challenge the rule, arguing it would allow plants to expand production without cutting pollution emissions and would undermine NSR.