A coalition of 16 states and 11 environmental groups is taking the federal government to court regarding the regulation of greenhouse gas emissions from new cars and trucks. The move comes exactly one year after a Supreme Court ruling that carbon dioxide and other vehicle pollutants fall under the guidelines of the federal Clean Air Act, and therefore require regulatory action from the Environmental Protection Agency.

The EPA has essentially ignored that order, forcing states to bring the battle back into the courtroom. “The court rejected the EPA’s claim that it lacks authority under existing law to regulate greenhouse gases,” said James Milkey, the chief of the environmental protection division at the Massachusetts Attorney General’s Office, in the New York Times. “It has the duty to regulate, not just the authority.”

EPA administrator Stephen Johnson has been criticized for dragging his feet on this issue for the past twelve months. Though he responded to the initial court ruling by saying the EPA would take actionable steps to reduce greenhouse gases, there were no signs of progress by the end of 2007. In March 2008, he announced that he would only make decisions about regulation following a period of public comment to gather more information—a move that was perceived as stall tactic by environmentalists and policy makers.

Many environmentalists see the EPA Administrator Stephen Johnson’s reluctance to take action on greenhouse gases from new vehicles as a direct reflection of the Bush administration’s lack of commitment to reducing carbon emissions.

On Wednesday, the states petitioned the U.S. Court of Appeal for the District of Columbia to force the EPA to declare its official position on greenhouse gas regulation within 60 days.