In Massachusetts v. EPA, the Supreme Court ruled that — contrary to the agency’s claim — EPA has the authority to regulate greenhouse gases under the Clean Air Act. The court also held that the agency could not refuse to use that authority based on the agency’s policy preferences. Instead, the EPA would have to decide, based on the science, whether it believed that greenhouse gas emissions were posing dangers to public health or welfare. If the agency determined that endangerment was occurring, the agency would have to start the process of setting emission standards for greenhouse gases. In late 2007, EPA officials sent a proposed endangerment determination to the White House as an e-mail attachment, but White House officials refused to open the document, and former EPA Administrator Stephen Johnson refused repeated requests to make the document public.
