The Bush Administration last week reaffirmed its March 2005 rule to control mercury releases from coal-fired plants through an emission-trading scheme. After formally considering the rule, as requested by more than a dozen states and five environmental groups, EPA determined that the rule's approach is sound, legally and technically. EPA also endorsed its choice not to use a technology-based approach to control mercury emissions. The 2005 rule marks the first regulation anywhere in the world of mercury from coal-fired power plants, but critics assail its provisions as too weak and its trading scheme as likely to cause hot spots where mercury deposition is increased. Critics also say the Clean Air Act requires technology-based controls for toxic substances like mercury. In a related action, New York Gov. George Pataki (R) last week announced plans to reduce mercury releases from power plants in his state by 50% by 2010 and by 90% by 2015 and to prohibit trade in emissions of this metal. In contrast, the EPA rule would curb emissions by 21% by 2010 and by 69% sometime after 2018.