This is about one of the Obama administration’s most ambitious environmental initiatives, an Environmental Protection Agency regulation meant to limit emissions of mercury and other toxic pollutants from coal-fired power plants. The costs to apply the new environmental rule was perceived as a punishment for the industry. Industry groups said the government had imposed annual costs of $9.6 billion to achieve about $6 million in benefits. The decision does not strike down the rule, but it means the EPA will have to review and rewrite it, with costs considered. An E.P.A. spokeswoman, Melissa Harrison, said the agency intended to move forward with the rule. The attacked EPA’s regulation was generated with intention to reduce industrial pollution linked in multiple studies to respiratory illnesses as well as birth defects and developmental problems in children.