California Attorney General Jerry Brown fired his latest shot against the federal government in his continuing effort to curb greenhouse gas emissions in the Golden State. Brown was in federal court on Tuesday attempting to force the EPA to release court-mandated studies about greenhouse gases and public health. The AG's office says the court proceeding is the first step toward establishing federal controls on greenhouse emissions. The Attorney General was blocked by the feds in his efforts to regulate emissions from vehicles earlier this year, although his office's efforts to reduce carbon emissions from other sources by 20 percent continue. On April 2, 2007, the U.S. Supreme Court ruled in Massachusetts v. EPA that the agency must regulate greenhouse gas emissions after making a formal determination that such pollution threatens public health or welfare. The EPA itself described the court's mandate as follows: "The EPA must determine...whether greenhouse gas emissions from new motor vehicles cause or contribute to air pollution that endangers public health or welfare." A recent investigation by the House Committee on Oversight and Government Reform revealed that the EPA had already made its endangerment determination--including an extensive scientific review--and sent it to the White House Office of Management and Budget for final approval. Brown called EPA's inaction "a textbook case of unreasonable delay" because the agency already completed its endangerment determination last year and is simply refusing to release it publicly. "The EPA said it would take action to regulate greenhouse gases by the end of last year but then broke its word and ignored the Supreme Court's mandate," Brown said in a statement. "The EPA has rejected the Supreme Court's order, an action which is outrageous and unlawful. We're taking the EPA to court to force it to do its job." Nineteen states and local governments joining California in filing the legal action include: Arizona, Connecticut, Delaware, Illinois, Iowa, Maine, Maryland, Massachusetts, Minnesota, New Jersey, New Mexico, New York, Oregon, Rhode Island, Vermont, Washington, District of Columbia, City of New York, Mayor and City Council for Baltimore.