Eighteen states, led by Massachusetts, as well as several environmental groups sued the Environmental Protection Agency (EPA) on Wednesday in an attempt to determine the agency to find out whether the greenhouse-gas emissions cause damage to the public health and if so, to regulate the emissions from new cars and trucks.

The coalition of states, cities and environmental groups said the EPA is disregarding the Supreme Court ruling that the federal government has legal authority under the Clean Air Act to regulate carbon dioxide emissions. The claimants urged the U.S. Court of Appeals for the District of Columbia to require the EPA to act on this matter within 60 days.
 
"What we have is an environmental agency acting completely contrary to its essential mission and duty," said California Attorney General Edmund Brown Jr.

The coalition of states and the federal government have disagreed over the regulation during the past years. The EPA refused to set emission levels for green house gases in 2003 arguing that the effects of the gases are still a “substantial scientific uncertainty” as well as the measures to counter these effects.

The coalition of states filed suit on the first anniversary of a landmark US Supreme Court ruling that the green house gases are in fact pollutants. The date was most likely chosen to illustrate the lack progress since then.

"Once again the EPA has forced our hand, which has resulted in our taking this extraordinary measure to fight the dangers of climate change. The EPA's failure to act in the face of these incontestable dangers is a shameful dereliction of duty," Attorney General Martha Coakley of Massachusetts said.

The EPA has concluded in December that the heat-entrapping gases are a menace to public health said the House Oversight and Government Reform Committee in a recent report.
However, the process of issuing regulations stalled after the EPA sent the results to the White House.

The White House Select Committee on Energy Independence and Global Warming voted 12 to 0 to subpoena all EPA documents as well as records of the agency’s resolution to stop California from regulating tailpipe greenhouse-gas emissions on its own.